XM Satellite Antenna Problem.....?

Although I am NOT new to XM Satellite, I am new to this forum and appreciative of it's existence.

I have a problem that I am encountering and I'm not sure if it's my XM Magnetic Mount antenna or the receiver itself. I only work 8 miles from my home and about 20 times each way, my XM Roady XT consistently loses signal. I have the antenna mounted on my Ford F-150 truck roof near the bed light. It is a USED antenna from when I had a Sirius unit.

Anyone have any ideas have an idea of what the problem might be?

Are you passing under trees or power lines on your way to work? Both will cause your reception to cut out.

I have an older Sirius called Stiletto in my older car which I have had for many years along with the lifetime service. Three years ago, I was having "acquiring signal" messages constantly and called Sirius. Up until that time, I had never had a problem with the radio. Sirius downloaded something that killed the radio, which they replaced, but which has had problems since.

I'm in a clear line of site and find that for the most part I can never get a signal. Doesn't matter if I'm on the freeway or in town under no trees on a clear day. I'm wondering if anyone has tried to permanently install their antenna into their radio system? I'm wondering if that would help with the signal issue. The car is too old to spend the money to replace the entire audio system, but I want my Sirius back.