Based on my experience with local alternator shops I would highly recommend you pull the alternator and bring it to them for bench testing and repair. They will be able to tell you exactly what's up and fix pretty much anything for MUCH less than even a rebuilt alternator. They can probably make it better than new in some respects too by picking better components to do the repair.
I had an aftermarket alternator unit (from a donor) repaired with a real Bosch voltage regulator (the orginal one was apparently of terrible quality) and now it's better than it was when it was new and it only cost ~$100 for the parts and labour including the testing he did for me.
You will save a lot of money by bringing them the alternator and not the whole car :)
--
1998 V70 AWD->FWD Turbo 200k+
|