You don't need a whole lot of pressure. 50 PSI or so should be plenty for checking. If you can borrow a portable air tank and a rubber tipped blow gun you will be able to check the clutches and bands. The bands are obvious as you will see the linkages moving. The clutches are not as easy but you should hear them clunk when you apply the air. There will be some air leakage even on a good sealing system but it is relatively easy to distinguish a bad leak from a good sealing system. Be careful as there will be oil showering down as you blow air into the various ports.