Is compression the same cold and hot? With the engine hot, do all the rocker arms for #2 become slack after the engine has been turned by hand to a position where the valves should be closed?

Note that the valves typically lose clearance as the engine heats up. If the rocker arm is still touching a valve it will not fully close, the leakage causes loss of compression.

That's about all you can do without taking the head off.