Hi Rick

I'm not a Line 6 employee, so don't shoot the messenger

Line 6's normal policy for stuff like this is not to supply parts or schematics to end users save for the odd replacement control knob or similar.   I only know this to be the case because of official Line 6 responses to other threads in the various forums on this site where people have asked similar questions to yours

The only ways you can get your amp fixed are to take it to an authorised Line 6 repair facility or to send it back to Line 6 for repair - again from official responses to questions like yours.  If the amp (you don't say whether it is a Spider III or IV) is out of the 12 month warranty period or if you've invalidated the warranty by attempting a repair yourself you will probably have to pay for the parts and labour unfortunately.

Any heat generated by whatever caused the amp to overheat and start smoking may have made the plastic in the controls brittle - particularly if the amp has been overheating for a while without you realising.

Nick