Holding a Cateye light

I'm at the bike shop still, even though my schedule says I should be gone. A guy bought a bike and he needs accessories installed and accessories transferred from his previous bike. I bought the previous bike for $40. It's an olive colored Trek 820 with a very large frame - probably 23". At 7:21, I'm holding his headlight and preparing to move it to the new bike - a corny new GT. At some point after this, I realize that my new $40 purchase might be a headache or a total loss: the seatpost is very much frozen. Aluminum in steel. Crap - I should know better. but I saw a deal, and I jumped at it. I want to build this bike into what it is capable of being.