Okay.. After reviewing the specs, The closest equivalent I can offer is our MJ10012. It's is somewhat lower current, but does meet the 400V.

Note-400V is very high for this type of transistor and this particular device (MJ10005) was designed into this circuit because of the high voltage which gets stepped up by the coil to 10KV+. This device also has fast rise and fall time which makes it very suitable for this application.

If you would like, send me your email address and I can send data sheets for both parts for comparison. The device we have as I mentioned has the high voltage, but the current is a little low. This will not damage the unit, but the unit may not function correctly, or could solve the problem.

If anyone wants to play around with a sample, send me you address, etc. and I will be happy to send you one at no charge.

If you want the actual replacement, I would suggest Newark Electronics from the link I provided in my last post

Best, Bob