Trouble with dash lights

I am having trouble with my dash lights intermittently working. I have already replaced the headlight switch but that was not the problem. I can take and hit the dash and they will brighten temporarily so I’m assuming it is a ground problem.

I am in the process of pulling the battery to check the grounds under the battery. Other than that, not sure where to check for ground connections. Does anybody have ideas on this?

2000 Jetta gls with 299k.

Update

Cleaned all connections under battery with no success.

When I push on the bottom right of heater control board, the lights work properly.

Is there a ground connection behind the unit that needs to be checked?

Any other ideas?

Make sure the connector to the rheostat is connected well.

https://www.idparts.com/panel-light-dimmer-oem-rheostat-a4-p-1217.html

2nd update-

Took everything apart (arm rest, center console, shifter cover and ash tray and was going to take glove box off but didn’t have to).

Connector to cigarette lighter seemed dirty (prevalent to spills due to location) sonI cleaned that. Reconnected and did a test drive with no dimming lights. Hope this was the cure!

Jokila - I did check connection while everything was apart and seemed good.

Road test last night for 5 miles on some rough roads and lights never flickered.

Those can be maddening. I had someone insert a small piece of cellophane down in mine just to tick me off. Took me a while to find it. Good thing I don't need one often.

Cheers,

PH

Final update -

After 200 miles on the road the dash lights are still working properly! Cannot verify with certainty what the issue was (electronics is not my forte) but am smiling again to be back in working order because I have a 3500 mile road trip coming up!

Cheers