Mk4 Golf - speedo and fuel gauges playing up

I've got a Mk4 GT TDI PD115 which I've had for about 18 months. Recently it's developed problems starting as follows:

At first around ~30mph the speedo needle would drop towards 0 and quickly recover. I took it on holiday last week (days after it went for a service) and the problem is now much worse - on a cold start it can take as much as 5 miles before I see any life from the speedo and even then it only works intermittently. If I turn the engine off and on again it seems to make no difference.

Also now when turning sharp corners I see the fuel gauge is dropping to empty and recovering (I get the "please refuel" warning on the onboard computer screen when this happens).

I'm thinking it's something wrong on the circuit board (dry joints maybe?) at the back of the instrument panel but that's only a guess. Does anyone have any other ideas or suggestions?

Also a guide to removing the instrument panel could be quite useful too. I've had a search of the internet and this forum but I've not found anything that seems to match my symptoms and nothing about accessing the back of the instrument panel.

Answering myself on this one - I disconnected the wire from the speed sensor on the top of the gearbox this morning and sprayed it with WD40 and reconnected. Also did the same with the connector on the top of the fuel tank (located under the cover below the centre rear seat). Took the car out for 10 minutes and so far so good.

Now all I gotta do is find out whether it's the hose or the joint at the top of the radiator causing my coolant leak :rolleyes: