10v stabiliser?

My erratic gauges are starting to make me sad.
For a sweet couple of weeks everything was working. I was happy.
I had "plumped" behind the connector and added an extra earth.
Then the mpg gauge stopped working, then the rev counter returned to its very erratic reporting and now I have no fuel gauge.
No putting it off, they have to come out again for me to check the connections.
Shall I replace the stabiliser too?
Where is a good place to get the part?
Any other suggestions of what might be wrong?
I should say, currently, the temp gauge is working, but who knows what tomorrow brings…?

Thanks!
 

It may be relevant to say that the rev counter seems to respond well to me pushing the clocks towards the front of the car when driving, i.e. it seems to work properly when I push the cluster with a finger…?
No effect on the errant fuel gauge though.

Fuel gauges can be tested in the cluster without dis-assembly.

If the Water Temp gauge is functional then it isn't the 10V stabilizer as it powers both the water and the Fuel gauge.

Bad grounds at the cluster is an issue.
So are the nuts that hold the mylar and makes connectivity to the gauges, they should be removed and polished as well as the mylar but on the mylar use a pencil eraser, and the nuts steel wool as well as the screw shafts.

The 10v stabilizer is a FA7810-aet you can get at a electric parts shop for less than a single USD, or you can pay 35-50USD for one from the dealer or parts store buy 2 or 3…

Improving your Cluster Connections and ground. | Volkswagen Owners Club Forum

Repairing your Fuel Sending Unit | Volkswagen Owners Club Forum

To test the fuel gauge in the car, use a 9VDC battery and apply the negative to one side and the positive to the other if the gauge deflects full scale and stays there it isn't the gauge. If it also doesn't deflect reverse the wires Key is not needed in the ignition.

If after replacing the ground and insuring that the 12V batter on pin 14 is good, measure for 10V at the Gauge with the power on.  

No 10V to ground on one side then you are looking at a bad mylar…You can jumper from the 10V leg of the 10V stabilizer to the nut on the gauge.

The input to the gauge is usually a Violet /black wire pin 3 that is the input for the gauge from the sender and Varies from about 23 ohms to 300 for deflection from full scale to empty.  If you ground it you should see the gauge move..if it does then you are looking at the sens wire break from the sender to the sender itself.

Thanks Briano, i will clean the nuts as you suggest.
The fuel gauge has decided to join the party again so i might wait till it takes the day off again.