Lubricating my early tachometer

[clevy70911T]

My 1970T has a tach that sticks around 2K rpm. I little thump and it will cross the 2k mark but then not come back down past 2k. Ssince it was sticking, I am going to try to lubricate it. Has anybody ever taken one of these apart without destoying the outer ring? I had an extra tach that I dissassembled but did ruin the outer ring in the process. It looks as though I can squirt some electronic cleaner spray after taking a couple screws out in back. It seems the only way to get in there without much risk of causing more problems. Thanks

Anyone have a better idea or advice? Ya know, you gotta have a tach swinging

Also, I'm thinking of selling, please pick my car apart on this thread
1970 911T, might sell, price it for me

Pics of my car here.
http://home.comcast.net/~clevy911/index.htm