Posting your problem with the Beseler 23C II difficult-to-remove/install lens board is useful. To better answer your question I disassembled the oldest of the three that I own. It had the same problem as yours. It took an inordinate amount of force to move the lens board far enough forward against the spring to change boards. This should be easy to do with a modest force. In the process I also disassembled a second 23C II so that I could analyze the differences and discover why #1 has the problem, but #2 works fine.
Here’s what I found. The difference is that the formed flat spring at the rear of the lens board retainer was incorrectly shaped on #1 compared to the spring of #2. By swapping the springs, the problem moved to enlarger #2 and #1 worked correctly. This seemed to confirm that the misshapen spring was the cause of the problem.
In my case, the small radius curl at one end of spring #1 was too long. It looked like the blank had been fed slightly out of position into the forming die in manufacture. Consequently, the spring had far too much force when tying to install or remove a lens board.
I remedied the situation by carefully grinding the excess off of the overly long end with the excess arc length. The other end was shaped correctly and looked the same as the spring on enlarger #2. The overly-long end was about 2mm too long to work properly. After altering the spring, the resistance to pushing the lens board forward against the spring to install or remove the board is now normal and the lens board changes are fast and easy—the way the Beseler designer originally intended.
In your case the spring ends might be correctly shaped, but the center arch might be too great. That will increase the force needed to install and remove a lens board, possibly by quite a bit.
If that’s the case, you can deal with the overly stiff spring by placing it on a table top with the large arch upward and push down to flatten the arch somewhat. If you overdo it, it can be bent back. This spring is only somewhat springy and can be adjusted without much trouble.
This is something of a “bend and try” process. What you’re trying to accomplish is to reduce the spring tension to reasonable value so that you can easily install and remove the lens board and still have the board safely retained by the spring force.
In order for the lens board retainer to work properly, the self-tapping screws that hold the front and rear lens board retainer plates in position must be fully screwed in. Leaving one or more of these screws partially loose in an attempt to fix the problem is a poor practice and doesn’t address the actual problem.
The Beseler 23C enlargers, all versions: 23C, 23C II, and the current 23C III, are well-made, robust machines that work well. Apparently in a few rare cases parts are sometimes slightly off-standard and might require adjustment.
Last edited by Ian C; 09-05-2012 at 09:59 AM. Click to view previous post history.