It is the only pump, where you can cock it, point it upward, hit the bolt release and it will completely fall out of battery.
So does it's child, the Ithaca Model 37. Both being based on the same design, they function the same. Especially the pre-war Ithacas had the same care and meticulous assembly by the craftsmen of that era.
My 1952 37 16ga is exceptionally smooth.
Mine works OK but I have retired it because the bolt lock-up seems a bit loose
Have a gunsmith look at the end of the slide release. Unless the mortice in the top of the receiver has been exceptionally worn out (very hard to do) or the bolt itself (also very hard to do), the part that simply keeps it where it should be at is the slide release. It does not take any of the bolt thrust, the mortice in the top of the receiver does that.
If you look at the design, the bolt locks into the mortice/cutout in the receiver and rides on the bolt carrier. There is a cam surface relationship between the bolt and its carrier.
If you work on this design, which includes the Ithaca, you can very simply move it in and out of battery IF the trigger guard assembly is not in place. There is no resistance at all to drop it out of lockup. It is a very brilliant design.
Sometimes the end of the slide release gets peened and allows movement that it should not. It is quite possible that the slide release from an older Ithaca might fit. It has to be one from the "slam fire" days though as the design was changed to prevent that.
I put pieces of both of these above posts together because they are both manifestations of the same design feature.