Yep the TOP243Y's blue caps are X7R and "glued" with transparent PCB lacquer. And now i am not affraid of high temperature, check following:

I have made a very comprehensive upgrades and repairs.
Backplate:

Whole subwoofer backplate with all electronics was dissasembled and the outside heatsing was removed too. Removed and cleaned all degraded glue and backplate was cleaned to aluminium gloss and all glue hard remants was grinded.
All pure aluminium heat conductive surface connections was filled with heat conductive paste and the edges was glued to prevent vibrations. Between outside black aluminium heatsink and the backplate was added heat conductive paste too.

New edge sealing and bass speaker sealing was applied.

[attachmentid=9697954][attachmentid=9697955][attachmentid=9668880] [attachmentid=9668883][attachmentid=9744125]

AMP boards, APB board and I/O board:

All electrolytic caps on amplifier boards and audio processing board was replaced by ELNA RFS Silmic II and bipolars was replaced by Nichicon MUSE.

[attachmentid=9668888][attachmentid=9668887][attachmentid=9668889][attachmentid=9697957]

[attachmentid=9697958][attachmentid=9697960][attachmentid=9668892]

All factory glued connectors and PCB pins was replaced by new ones and all wire contact was crimped with new contact crimps.

[attachmentid=9668891][attachmentid=9697961][attachmentid=9697981][attachmentid=9697982]

Audio processing board was separated from I/O board and soldered new contact pins and headers to make it detacheable. Input cable was removed and soldered
JST-XH 8 pin header and custom cable made for connection to PSU board. New custom made signal cable from audio processing board to amp boards used.
Almost all cables was tied together with cable ties. Removed all degraded glue from I/O board and I/O connectors was resoldered with fresh solder. Replaced all JST-VH conn headers.

[attachmentid=9697963][attachmentid=9697964][attachmentid=9697966][attachmentid=9697967]

[attachmentid=9697994][attachmentid=9697976][attachmentid=9697968][attachmentid=9668951]

PSU board:

Replaced mains power switch and grid input connector with grounding pin connected to backplate with yellow/green wire.

[attachmentid=9697969][attachmentid=9697970][attachmentid=9697971][attachmentid=9697972][attachmentid=9697973][attachmentid=9697975][attachmentid=9668896]

Replaced all electrolytic caps for high quality ones (Nichicon, Rubycon) and the most of ceramic caps.

[attachmentid=9668900][attachmentid=9744111][attachmentid=9744113][attachmentid=9744114][attachmentid=9744115]
[attachmentid=9744117][attachmentid=9744118][attachmentid=9744120][attachmentid=9744121][attachmentid=9744122]
[attachmentid=9744123][attachmentid=9744124]

Replaced all TO220's aluminium oxide heat conductive pads (lot of them brokes when disassembled) with heat conductive paste. Custom made linear reg / diode heatsink, shape silmiliar to IRF740 heatsink. Custom made carrying L shape heatsink. Added ribbed heatsink for better heat dissipation. (ebay sourced)

[attachmentid=9668902]

All heat sink connection surface filled with heat conductive pad sheet. All screwed together and screws was glued or transparent protective PCB lacquer lacquered to prevent unscrewing. The most important thing was connect the carrying L shape heatsink to backplate with heat conductive paste for best heat dissipation and tightened using 6 screws with self locking nut and the edges was glued.

[attachmentid=9668904][attachmentid=9697977]

Part of PCB copper pad under heatsink connection near D13 was scraped off to make it unconductive to heatsink. Heatsink side of L11 near C20 was unsoldered
and heatshrinked and glued to PCB.

[attachmentid=9668907] [attachmentid=9668911]

This makes the heatsink conductive isolated from the power supply board and the mains grounding wire can be safely connected to backplate and now can fulfill its function.

[attachmentid=9697978][attachmentid=9668898]

After this upgrade the heat dissipation is much more better than original which can guarantee much much longer lifespan. In the standby mode the outer heatsink
is hand touch cold. In power on and common use the backplate and heat sink after some time are hand touch warm but not hot (about 35-40°C).
For the even better heat dissipation the outside heatsink can be equipped with FAN which can lower the temperature to lukewarm if used low rpm and low noise FAN.

[attachmentid=9668912]

Upgraded active cooling with 140mm low noise FAN less than 20dB at full rated speed.

[attachmentid=9697979][attachmentid=9697980]

Wooden case:

Wooden case all internal edges was reiforced with new glue and after then whole case was damped with wadding filling. Bassreflex pipe was removed and newly glued.

[attachmentid=9697983][attachmentid=9697984][attachmentid=9697985]

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All inside

[attachmentid=9697987][attachmentid=9697988][attachmentid=9697989][attachmentid=9697990][attachmentid=9697991]

After this case upgrade the bass are deeper and louder about 2-3 dB compared with the wooden case with no filling. Compared both with the same master volume
and SUB volume settings.

Hello, thank you. Here is the capacitor list i've used:

PSU board:

CK45-R3AD221K-NRA CAP CER 220PF 1KV RADIAL  C2 30 28 29
RDER73A471K2K1H03B CAP CER 470PF 1KV X7R RADIAL  C39 35 36 37 38
AR205F104K4R          CAP CER 0.1UF 50V X8R RADIAL  C63

LGR2D471MELZ40  CAP ALUM 470UF 20% 200V SNAP C59 60 69 70
100ZLJ330M12.5X35        CAP ALUM 330UF 20% 100V RADIAL C71 72
35ZLJ220M8X16  CAP ALUM 220UF 20% 35V RADIAL C64 73 74 75 76
50ZLJ100MT78X11.5        CAP ALUM 100UF 20% 50V RADIAL C65 78 66 67 77

450BXW68MEFR14.5X40 CAP ALUM 68UF 20% 450V T/H  C61
35ZLJ47M5X11          CAP ALUM 47UF 20% 35V RADIAL C68 62

DE1B3KX471KA4BP01F CAP CER 470PF 300VAC RADIAL  C7

CC45SL3FD470JYNNA        CAP CER 47PF 3KV SL RADIAL  C3
C317C101K2R5TA  CAP CER 100PF 200V X7R RADIAL C9 46 45 44 43 42 41 40

RDER73A332K2K1H03B CAP CER 3300PF 1KV X7R RADIAL C6
RDER72J103K2M1H03A CAP CER 10000PF 630V X7R RADIAL C20 19 17 18 
RDER72A104K1K1H03B CAP CER 0.1UF 100V X7R RADIAL C11 53 12 13 52 10 48 49 50 79
RDER73A472K2K1H03B CAP CER 4700PF 1KV X7R RADIAL C8
       
Amplifier boards:

UHW2A102MHD          CAP ALUM 1000UF 20% 100V RADIAL  C39
FK22X7R2A105K  CAP CER 1UF 100V X7R RADIAL          C40
RFS-50V2R2ME3#5  CAP ALUM 2.2UF 20% 50V RADIAL  C86 89 85 88 84 87 91 81
RFS-50V220MH3#5  CAP ALUM 22UF 20% 50V RADIAL  C211 79 83 78 82 77 90
UES1H4R7MEM          CAP ALUM 4.7UF 20% 50V RADIAL  C28 69 22 37 27 68 21 36 26 67 20 35 80

Audio processing board:

RFS-16V470MG3#5  CAP ALUM 47UF 20% 16V RADIAL  APB C208       
RFS-16V100ME3#5  CAP ALUM 10UF 20% 16V RADIAL  APB all 10uF
RFS-16V101MH3#5  CAP ALUM 100UF 20% 16V RADIAL  APB C220 218 202 201 221 219       
UES1H4R7MEM          CAP ALUM 4.7UF 20% 50V RADIAL  APB C54 52 58 56 39 40 16 18 17 15

Relay clicking issue fix:

FG20X7R1H106KRT06 CAP CER 10UF 50V X7R RADIAL  added another C63
FK26X7R2A104K  CAP CER 0.1UF 100V X7R RADIAL added between TOP243Y's C and S PIN
FK26X7R2A105K  CAP CER 1UF 100V X7R RADIAL  added between TOP243Y's C and S PIN