HELP with FLUKE-6070A - Error 120

[Lex-Lutor]

I have problem with my FLuke 6070, after power-up there is error 120 at
right end display, it is error 100 and error 20, so I can`t use
AM-modulation for testing. Since I don`t have service manual it will be nice
for few infos how to repair this problem.

Thanks for any help !!