You will need a vacume gauge to check that the modulator is getting vacume. You can get a cheep one from a department store for under $10.00 US. All you do is disconnect the vacume line at the modulator and plug in the vacume gage. I havent done this in a while so check my numbers but I belive you should see more than 18" vacume at idel. To check the Vacume modulator you will need a vacume pump. You just connect it to the modulator and pump up a vacume and see that it will hold. You can get a cheep one of these from and auto parts store for about $30.00 US. But be carfull the cheep ones tend to leak down themself giving you a false indication. Even the good ones do this occasionally. So you need to test you vacume pump before you start by holding your finger over the vacume pump inlet and applying the vacume and makeing sure the pump holds vacume all by itself.

John Roncallo