If the bikes that old, it probably has a loose ball bb.
It WAS a repairable system, but if it's been run with worn ball bearings or without lube the races (channels the balls roll in) get pitted.
Then its garbage.
I recently had a cartridge bb installed...$22? and $17 labour.
The cartridge bb require no lube, they are just replaced. 5 year life span probably.