Firing Ushio Using Tar Ballast

[PeterW]

I recently bought a tar ballast with pulse start and am using Ushio 175watt bulbs. The problem is they don't fire up properly.

Even when the bulbs are screwed in very tightly in the mogul. It would remain unlit even having the ballast on for hours.

It needs a little jiggle and then would fire up. This means I can't put the MH on a timer.

Right now the bulb sits on top on a glass top. Any ideas? Is this the right ballast/bulb combination?

Thanks in advance!

Peter