I have a pair of Penta MK1 with one kind of minor problem, the "door" (where the controls for sensitivity, bass level and power mode) can't be closed. When I press it to close it, it just clicks but it never locks the "door", it just opens at once.

I wonder if anyone knows how to fix this, is it hard and what's the cost for the parts.

Your B&O dealer can still supply a new door latch and fitting is relatively simple.

Ask him to order 3034066

Behind the lid there is a spring to open it. After the repair don't mount this spring anymore. This will prevent the problem happening again, and without the spring the lid opens without any problem.

FYI, my US B&O Dealer has this part number updated to: 3034003 Not sure if it's the same worldwide, but wanted to let let people know in case they are trying to order this part.