PRNDS Selector Lights all on Randomly & Stiff Gear Change

[steamship]

Have been lurking here a while trying to find out what's what with my A8 and any gremlins they come with. On a recent 370 mile photo trip, I noticed that all the selector lights were coming on. This usually occurred during three and four point turns down single lane roads and tracks. Wasn't sure at the time what the problem was, so switched off and on again, which cleared them. Have since come across several posts suggesting it might be the F125 switch on its way out.

However, I suspect I have a more pressing issue which may put the F125 switch issue into perspective. I was parked up yesterday for another half an hour on a 30-35 degree slope. When I got back, started the car up, and went to move it into drive. Had to use quite a bit of force to move it and there was a clunk when it moved from P to R. Not being mechanically minded, even I know that this doesn't sound good.

I've read other posts about replacing the gearbox and diff oil, and was wondering if what I described are signs of there not being enough oil in the transmission. That's question one. The second question is whether anyone knows someone who could check and change the oil here in Northern Ireland, who knows what they are doing. I've already had help from one of the forum members in respect of a contact for a LPG conversion.

BTW The car is a 2001 3.7 QS with only 55k on the clock. The car drives fine. Any help would be much appreciated.