Triceps vs. Machine

I have recently discovered that I would rather lift weights for 2 hours than run for twenty minutes. Having said that, I have yet to master the weight machines at the gym. I LOVE working my triceps, but for some reason all the machines that work them are ridiculously hard to figure out! I finally found one that you just rest your elbows on and pull down on a weight. Something I can handle, right? WRONG. It totally kicked my butt. At one point I thought I was either going to break a tendon or pop out an eyeball! Its been two days, almost three, since I sat at that machine of death and I can hardly lift my arms!!! I was just in the shower attempting to shave my arm pits and all I could do was laugh and cry because I couldn't lift my arms high enough to get the job done. *sigh* That machine better watch its back, because imma take it down next time it gets in my way.