Just contact this place and have them restore them for you.
The 15
https://nelionaudio.com/index.php?/services.html/carver/carver-amplifiers/carver-tfm-1515cb-restore-r23/
The 35
https://nelionaudio.com/index.php?/services.html/carver/carver-amplifiers/carver-tfm-35-35x-restore-r10/
Don't know if a kit exists but for the most part if it does it will probably not address any hidden problems.
Statement from their site on just the 15, (read about the 35)
"They need to be serviced properly!
The restore for the Carver TFM-15(cb) amp includes replacement of all consumable parts, output relay, reflow of critical solder, all service bulletins, cleaning inside and out. The unit is fully tested to spec, burned in, and played on our critical listening rack and speakers."
You will get them back better than new. Best money you will ever spend.