Starter, flywheel problem
In need of help guys.....I bought a 69 911t which had a flywheel with teeth missing which in turn created a starter issue....I then dropped the engine, replaced flywheel ,clutch, rear main seal , pressure plate, new high torque starter ect....3 months later I heard a familiar ugly noise, then starter squeal.....removed starter and with an inspection mirror looked at the flywheel...teeth missing again....😩.....can anyone please point me in the right direction to what may be causing this problem....I don’t want to replace all parts again only for it to happen a 3rd time.....any help would be very much appreciated.