Hillman Hunter fuel gauge

Hi, Just a quick question when i start up out 1971 1725cc Hillman hunter the petrol gauge gos up to what i bleive to be about right bear in mind i live on a hill incase this has an effect. then by the tme i drive to the bottom of the road it gos down to E and stay there despite parking in the same place when i come home on the hill i have tried cleaning the contacts on the sender underneather the car i was wondering if any one has had a smilar problem with one weather it was the gaguge or the sender in some ways i hopes its the gauge as it looks like i would have to drain the tank to get to the sender out. this car has nevr had this problem in the 30 + years we have had it. Also i was think of hand painting it with normal household gloss paint i have been mucking about painting gloss on to scap metal and have found with a couple of coats on and leaveig it to dry for a few days i can rub it back to quite a nice shine has any one any dealings with this ?? and the pitfalls?? Many thanks George