What things should I look for when buying a used head and cab?

[Snow007]

I'm about to purchase my dream amp, a Marshall 1987X along with a cabinet, either a Marshall 1960AX Cabinet or Marshall 1960BX Cabinet. I have played both cabs through the amp so I know it works and am leaning more towards the AX but I'd appreciate if I could get some advice of what to look for that could be damaged before I go out and spend so much.

[dk1ben]

My first thought is to play it. Loud, Low, Fast, Slow. Put it through its paces. And of coarse physical damage is important to look for. Not sure what else you should do without opening up the head or checking the condition of the wiring.