PS1 Not reading games

I recently tried repairing my old PS1 but the system gets stuck on the opening white screen with the Sony diamond logo. I cleaned the lens and greased the rails in the optical drive so the lens housing can move easier. I also cleaned up any dust and debris inside the unit and didn’t find any obvious corrosion on the board. Does the optical drive need to be completely replaced or could it be some other issue? I’d also like to turn this new hobby into a side business. For future reference, is it worth replacing an optical drive in a PS1 with a new part or would it be best to find one that works from another junk system?