oil pressure gauge not working, Help!
 

I replaced a leaking heater core over the weekend, while I was at it I took all of the ducting out of the dash and pulled the ducting out to clean all of the dust out of it.
I'm trying to get as many issues taken care of as possibile , I'm going to drive from Northern Alberta to Washington state in July.
So the criuse control wasnt working and I decided to pull the cluster to see where all of the components were module etc.
Got everything working , and back together and now I have on oil pressure gauge. it points straight up regardless, power no power, key on or off.
Im thinking I distrubed a ground somewhere along the way. any ideas where to start.
Remember its a 91 with the electronic cluster.

Thanks

Keith