I have the 1541U1 too, and it works fine here. Have you tried the last inoffical firmware (2.6d.0918.4)? It's been a while, but it solved a lot of issues back then. I can send it to you if you want.
Hello. Thanks for the offer, but I fear, that sadly i can't use this unofficial firmware, because, like i wrote, my 1541U1 is one from the very first batches that was released back then, without REU and also board is little bit smaller than the later versions. It was always said, that the latest version you can use with such an old 1541U-MK1 (not MK1+) is V1.72b and with this, the crt dont work. Or is this firmware also for very old MK1 devices? But okay, i am sure, sooner or later a diskversion of the game will come anyway, either from Monte Boyd itself, or from other people.