ALL Amiga 4000 need repairs.
What about one that's just been repaired?
If it ain't broke, don't fix it I say. You may be correct in saying "ALL Amiga 4000
will need repairs," but if it's currently working, changing parts wouldn't be considered a repair, but preventive maintenance.
As for this thread, it has chronicled ceaser's complete disassembly of the machine in what could be considered amateurish attempts at repair. I wouldn't expect the seller to take responsibility for a machine that was pulled apart and poked at by someone who may or may not be qualified to do so, not that this seller had taken any responsibility in the first place. No guarantee means no guarantee.