They were never designed for gaskets. If you need more room, get the spacer that opjose suggests... or see what causes the problem you mentioned. I had the Nexstar and mine did not have any spacing problems at all.

Is this the one that you had problems with the engine mount? If so, perhaps you should have followed the instructions from where you bought it from and sent it back. This is beginning to sound like it's not going to make it past the maiden flight.

CGr.