Larry, you are confused about this-a removable sidelock double might be easier to DIAGNOIS trouble on-it isn't and won't be easier to fix than a boxlock. No way.
And, I'm sorry to break this to you, but, if you have trouble with a detachable sidelock gun, you will have to use something to get the screws out-they don't fix themselves because you removed the sidelock and looked at it.
You understand that there are screws (pins) in a sidelock, right Larry? Usually its just OWDs that I have to explain this stuff to. You might be surprised how much actual time I've spent repairing decent double guns, Larry, especially sick Darnes when I was the only parts source, let's see, in the western hemisphere.
There is no mystery to fixing a boxlock, one does need a few boxlock specialized tools, but, the parts are fewer, and easier to fit and regulate. That, in a nutshell, is why a boxlock is cheaper to begin with, cheaper to fix, and cheaper to maintain than a sidelock.
Pumps being cheaper than good doubles doesn't really surprise me, but, I'm happier that they are. They also will put up with more abuse and use than the doubles they competed against, and a gas station mechanic (as opposed to a good gunsmith-I've fixed plenty of those things, too) can usually get them running again. So, Grandpa actually did get his money's worth out of that 31 or model 12 or whatever, if you really think about it.
Best,
Ted