I use a regular automotive air compressor, the small 12 volt type sold in many places.

If you have that small air valve that Robart makes, toss it and get a regular schrader valve. You can them from Sierra Precision. It makes life so much easier.

As for your proble, we need more details to help you, but I usually use a pair of clamp type forceps, sometimes two of them, to pinch of various lines to islolate leaks, etc.

Beyond that small tip, I don't know what else to tell you for now.....