I've got a 23c... To clean the condenser, crank the lamphouse all the way up, to the "35mm" position. Then, pull firmly down on the top end of the bellows assembly; it'll slide off the condenser housing, just held in place by friction.
Then, the condenser ass'y slides out toward you the same as the filter tray. From there it's just a few screws and careful handling.
As for the lensboards, many of them were sold with a threadless hole, to be used in conjunction with a threaded nut. Annoying isn't it?
I hope working in the dark is as satisfying for you as it has been for me.