I'll be humble and say that these machines "suck" for lack of better words, because I don't want to be removed from this forum, lol...
Check the blue coin validator for jammed coins and clean with compressed air. Then you must unplug machine to reset it.
Clean or service bill validator. There are shops that sell and service ict, you'll have to check online or call ict.
The compressor can be removed and fixed, I'd replace the machine instead.
You can order a key pad online, but you're risking to buy a defective part that may not work on your machine. Try cleaning the buttons with an alcohol solution and spray with compressed air. Make sure all your connections are plugged in properly throughout the machine drawer, board, etc.