Why the shock absorber? Consider the competition. Mercury made a big deal of their “No shear pin” ads. They had that splined prop shaft with multi-disc slip clutch inside the prop. Sort of worked, according to how easily the clutch slipped. Other companies also came out with their slip clutches. Anyhoo, OMC had their slip clutch that worked–the shock absorber in the gearcase, bathed in oil.
The shock absorber is in three parts, the upper and lower section housings, and the spring inside. In relaxed state, the spring is a tad larger than the ID of the housings. Pressed into the housings, the spring is compressed and grips the housings tightly. When an obstruction is happening, the spring winds up, becomes smaller in OD, and loses its grip. Then unwinds again after obstruction, and regains grip. Now for the mysterious part: It never really happens, but just suppose the spring was wound up enough to completely lose all grip inside the housings. In that case, the three parts would be free to move apart, making the assembly longer until limited by the bearing housing above it. That limitation in itself if not enough to cause jamming. But suppose you were to take it apart and replace the bearing housing or gasket, or otherwise reduce the clearance. Now it’ll jam. Pressing the shock absorber back together restores the original length and good as new.
The other scenario, of course, is the infamous broken spring. There isn’t enough room in there for the broken ends to pass each other, so it all expands and all else ceases to fit.