300tdi alternator repair

Since the mystery burning of my jap auto 300s alternator yesterday I am looking at repairing it,£20 ish instead of replacing it,£100 ish. The unit is a marelli trype but of the A127 design with stud connections.Most of the kits offered appear to be for the lucas type with the closed cup rear bearing and of lower amperage.

Does anyone have experience of repairing these units and sorces for kits ? I am waiting on replies from 4 factors at present and have found a series of videos about reparing the similar lucas type...

A127 Alternator Rebuild Part 1/6 Video – 5min.com


...I am no closer to finding out what caused the unit to burn up after 6 plus hours of running OK....would be nice to know so I dont do it again and cook another.

When questioned about visible differences,the 20quid suppliers admit that the kits DONT fit marellis.The only supplier who has got back to me with one that DOES fit wants £78+vat+p&p....I was offered a new one,120amp,years ticket,90 quid,yesterday !