The door catch, MB P/N 123-720-01-04, sells for $27.50 from
any MB dealer, plus the rivets (new), 4 required, run $0.50 each
for $2.00 total, MB P/N 116-990-00-31, and those items should
remove the cone cylinder malfunctions on the pillar "B" chassis
for a 123. It is not recommended to use wet lubricant, except
in emergency, but a dry lubricant for door hinges. There is a
"trick" for removal of the countersunk allen head rivets, which
reveals itself eventually; realignment of the hidden shims inside
the "B" pillar should be attempted while relaxed and sober. If
one were to cause the behind shims to drop to into the lower
cavity chassis there would be little real hope for recovery.

Good luck! This is a DIYer project to rid the 123 of locking catch
malfunction when identified directly to the cone as defective.