I reckon rebuild the HV section.

I have a display on my Royal Rumble that does the same thing. Works perfectly for 50 start ups, then goes funny for 3 or 4 start ups then shows all lines lit up and does weird stuff. I took it out and shoved it in another machine and it did NOT do anything weird. But the other display I put in the Royal Rumble started doing the same weird stuff which it had never done before, so I know its a votage issue and I will get Beaky to check the dmd driver board/and the voltages in general.

IF you are going to buy a new DMD, Mad Amusements in the USA have them for $129, postage is around $25 to $35 and the more DMD displays you buy, the cheaper they are and the postage drops as well. A good idea would be to order for ya friends and mates who also want a new DMD display and share in the costs.  

http://mad-amusements.com/product.php?id_product=236  

I tried local suppliers, but they cannot match the USA supplier who buys in bulk.