[blackrosenova400]

I dont believe tightening the front cover too tight would cause your oil pump to wear like it did. It would literally have to bend the front cover to be able to cause abnormal wear.

On the other hand tightening the back gear over where the balance shaft came out, too tight, could cause gear endplay too be too tight on the gear and it would chew up as it did.

Show us a pic of the front cover assembly, I want to see if its a legit Mitsu pump.