Very good detailed report......from what you have written, I would swap the plasma systems from one machine to the other. You could actually first swap just power supplies......if that made no difference then swap the torches and leads. There are a few things I can think of that may give these symptoms:
1. If the problem stays with the machine (does not follow the plasma)....then there may be some type of plasma start signal "bounce" that could be caused by electrical noise from the plasma power supply initial inrush current. You could trouble shoot this by jumpering the input start to the plasma instead of letting the Dynatorch output for the plasma.
2. If the problem goes with the torch (but not the power supply).....there could be either a restriction or a leak between the power supply and the torch that is causing an abnormally slow air pressure increase to the torch.....this air pressure is used to pull the electrode away from the nozzle....which creates the spark for ionization of the plasma gas.
3. If the problem seems to go with the power supply.....there could be a bad (sluggish) air flow solenoid.....or a leak (or restriction) in the internal air plumbing.
4. Missing or leaky torch body o-ring.
Usually a misfiring Hypertherm Powermax torch is caused by a. overtightening of retaining cap. b. defective or worn retainaing cap. c. aftermarket consumables (tolerance issues, usually from American Torch Tip parts) d. defective or worn swirl ring e. high moisture or oil content in air.
Let me know if I can help in any way....also, have you worked with Hypertherm's tech service? They are usually very helpful....and free!
Best regards, Jim Colt Hypertherm