Have a look at the link below. It's a reprint of an article from Light Plane
Maintenance (ANY article you read in that rag should be digested with
caution). I haven't read the article in full but towards the end they
mention that Lord Corp can rebuild your coupling for a LOT less money than a
new unit from TCM.

If you have a look at the elastomer in the coupling and it's a kind of light
brown color it's no good. If it's kind of a red silicone color it should be
OK. I got this info from a Lord rep years ago.

Bob Young is right about removing and replacing the alternator. I made a
quarter inch drive crow foot of sorts out of a 12 point box wrench to do the
job. It's the ONLY thing I found that works on the TCM 100 amp alternator.
I've seen guys use a punch and a hammer but I won't do it.

Installation of the coupling on the alternator is tricky and you should
reference TCM service bulletins and their alternator overhaul manual. If you
don't have the knowledge, tools, and data don't do it.

Holding the coupling while removing the retaining nut can be tough. Don't
clamp it in a vice. Put a worm drive hose clamp around it nice and tight
then you'll have something to grab on to keep the coupling body from turning
while you loosen/tighten the nut.

The quickest way to check a coupling on the plane is to run it up to about
1500 rpm or so, watch the ammeter, slowly add load (turn on landing lights,
etc.). If you see a sudden drop in charge rate you probably have a bad
coupling.

http://www.lordcorp.com/news/2001/tcm_gear_driven_alternator_checks.pdf

Ted Stanley - A&P-IA