Bohm Klingenthal MV 2 - welche röhre?

Hello

I'm sorry that I can't ask this question in german but I'm norwegian and can't speak any german.

I have an amplifier, made by Bohm Klingenthal, called MV 2, that I boght in Berlin two years ago. It sounds very good, but now the tubes needs to be replaced, but it is impossible to read what type the output tubes are because they are so old. The preamp tubes are ECC83 and the rectifier is EY81. I tried replacing the output tubes with EL84's but then the fuse blew immediatetely.

Any suggestions what output tubes to use?

Thanks!