does it have oil in it?
i have a normal compression tester, you don't NEED a rotary tester.
just make sure you get three even bounces on each rotor.
if you are good you don't even need a compression tester, if you hold your hand , or hell just listen for 3 even bounces of air comming out of the spark plug hole.
if you are real good i heard you can also pick out six distinct bounces out the exhaust....