Jeff Rowland Consonance display problem

I am hoping that you guys can help me with a problem that I am experiencing with a Jeff Rowland Consonance pre-amp. After about a minute the display starts fading, eventually dying. The display remains dead until the power is removed for about 10 minutes when it then returns for another minute or so. It is a flourescent display, and when it is dead I can hear a faint buzzing noise coming from it.

Regards

Dirk