I have 6 new, one second hand here. Don't worry about stocks - I have about 100 damaged repairable displays (both Mk 1 and Mk 2/2A), a great deal of which simply have component failures. The stuff isn't cheap, I'm afraid, but it is available and I am selling the stuff on at cost price to make sure the price stays as low as I can keep it. I am likely to be buying a batch of stock sometime in the next few months.

As for the problem with the display - the interleave problem is a failure of one of the raster controllers inside the glass. It can manifest itself as either a low voltage from the power supply from the display board (under about 48 V) or as a result of the tube getting a bit gassy. You can check the first with a voltmeter (probe the lead of the large black capacitor nearest the inductor on the right hand side of the display as you face it, on the back of the board). You can see the second (look in the display glass with the lense removed at the corner near the nipple and look for a light, white-coloured deposit on the inside of the glass - like mist). The first can usually be sorted out by repairing the power supply, the second is not recoverable