I've not used my MX4000 for a while (18 months or so) and have begun using it again in my kitchen, however, it keeps turning off after differing intervals. Sometimes it will go for 30 minutes before switching off and sometimes only a few minutes - can anyone offer any help?

FYI - I've had it from new (1993) and it had a replacement chip/board(?) fitted by B&O 4 years ago or so because it wasn't turning on at all - not sre if this has any relevance?

Many thanks