1974 M20F Fuel Gauges Sticking

[AlbertF]

We’ve had this issue increasing in severity over the last year with the fuel gauges sticking and needing a thump after turning on the master.  We have to tap and ever so harder over the months to get them to respond.  During annual, our mechanic said there is nothing he could do as all the connections are good.  I opened up the cluster and see that the needles are very delicate and need to be gently tapped to respond after the master is on.  Attached is a close up of the mechanism.  Anyone had this issue?  I’m thinking of using a cotton swab with alcohol to clean at the pivot points.  Should I also use a lubricant?  The parts are very delicate so I don’t want to damage anything, but I also don’t want to have to tap hard on the gauges every time I fly.  Thoughts on how to remedy?

[carusoam]

If there is a way to clean them.... they aren’t very strong, and may be dirty...

There are a couple of choices for that...

Get the gauges OH’d...

Or consider major surgery and get a digital primary instrument...  EI, JPI, or big G....

PP thoughts only, 

-a-

 

[Learreply]

Hey Albert,

 

I would not use alcohol. Even the 97% stuff will leave a bit of residue. 
 

you could try Mass Airflow Sensor cleaner. It should clean well, and not leave a residue, as well as be gentle on the copper. 
 

that should get you all fixed up, but if they are still not working well, then try a bit of light oil on the pivot point. 

[AlbertF]

Thanks for the points.  I’ll try MAF sensor cleaner.  Small amount of oil if still sticking.  

[brad]

Been tapping mine for 10 years.  Never changes, so I live with it.