Bouncing temp gauge !

[mak595]

The temp gauge on my 31k kidney clocks bounces, it works ok and reads as the temp goes up. 

Before  I strip em down, has anyone come across this?

Is there some kind of spring to dampen the movement?

[tacky1]

Unless there is one inside this thing. I usually just replace them, I took this pic 5 mins ago, I was rebuilding a set yesterday

[roach3]

i had this on my 31k, the needle would dip to zero as i revved the bike like a tacho needle in reverse
noticed when i had a look at it that the needle was very loose and would swing around very easily instead of a slow return back to the stop
replaced it with another and its now bang on.