Hey, posted in  my thread 'the tabasco fiasco' but i thought it may be ok if i post here too.  My tacho (DT125 monoshock) is on xanax it rises to 4000 4500 and then doesnt do much, at a halt it comes back down to idle, slowly, right now my ears are my best tacho!  What should I be looking at.  So far I've been waiting on some issues to see if they resolve themselves, this being a bike that  probably has sat for quite some time, so lots of rain, dust, sun and I dont want to fix what isnt broken or break what is working.  So far wrenching and riding has been a crazy blast - thanks for you help

Best thing to try is inserting a cotton ball damp with kerosene into light bulb hole(s) in back of gauge....  keep gauge FACE UP during the whole process.  You don't want kerosene dripping down inside and getting on the lens or face.  Leave face up gauge out in sun for at least a couple of days.

The fumes from the kerosene will gently "revive" the delicate internal lubrication and almost always restores operation of a sticky speedo or tach to normal. 

If that doesn't work, I'm not sure of a way to get inside the later plastic gauges that doesn't destroy the housing...  and when inside, pretty delicate movement you'd have to be very careful with.  So hopefully the "old clockmaker's trick" of kerosene on a cottonball works for you. 

Now that is one hell of a piece of advice. Genius!

Just to discount it being the cable or drive, maybe use a power drill (anti clockwise) with an old cable inserted and see if it still does it.

Cheers guys
yes sticky tacho needed lubricating. I have to test it, but I decided to remove it and managed to disassemble, I glued it back with white wood glue (so I can easily remove if the fix didnt work) and then electrical tape. I'll post some pix and let you know. Looks like the tach houseing was glued, but it just popped out when I had a go at it. The kerosene 'trick' is great, will have to try that one day