Per OP description of a shop job.
Full playfield tear down
Full mechanical rebuild
So that means everything gets cleaned metal tumbled, inserts cleaned, PF waxed, assemblies disassembled, cleaned & rebuilt.
Rebuilding pop bumper assemblies.
Four flipper assemblies to rebuild.
Let not forget about spending a couple of hours dialing in game so it plays great.
Price $800 to $1100 depending on location and if transportation is required.
People who are saying $300 are doing charity work or might not know what’s involved.