Erratic Speedo?

[Tino-m30b35]

Hey,
My speedo jums up and down while driving. Almost as the signal goes on and off ( i know the speedo sensor sends a pulsing signal, but is like the gaps between the pulses is longer), a tap on the clocks usually fixes it for a while.
What can be done to correct this?
Loose connector? Faulty wiring?

TIA
Tino

[jlevie]

That sounds like a bad connection or failed solder joint.

[M-technik-3]

Possibly failing SI batteries.

[Tino-m30b35]

That sounds like a bad connection or failed solder joint.

So I'll have to take it out and check. Thanks

Possibly failing SI batteries.

Most Probably, beacause I can reset my SI and once I start the car again, it will go back to red lights.
Must I replace with BMW batteries? Can't I just put in rechargeable AA or AAA batteries?