Hey guys I'm new to this forum and I owned a jeep but a my sister recently got her license and bought this 93 ford escort cheap without my help. Anyway point being is sometimes you have to tap or hit the right rear tail light to light up and sometimes it works like normal. The drivers side and third brake light works fine. So I pulled the bulb and cleaned the very little corrosion out that was still there but it just started acting up again a day or two later. I'm on a tight budget and want to figure it out so incase it happens again I'll know what to do. I'm thinking its a ground problem but I don't want to be looking the entire car from the tail light to the fuse panel because it would take about two weeks for me to do. I was hoping someone ran into this before and found a fix for it or atleast able to narrow down what ground locations to look for. Any help what so ever would be much appreciated.

Remove the light and clean every connection you can see.

Sounds like it's loose or dirty.