I suppose the same (travel bouncing) can be said for any cylinder. I did not rebuild mine. It does drift down, over the course of a day or two. Certainly not worth rebuilding to me...... I hauled it on a trailer, and the lift "tongue" (part that goes up and down, looks like a huge tongue) was on the deck of the trailer. Don't see how that could have been an issue. It's interesting though...
The tongue pivot point is where the cylinder raises and lowers the snowblower. So when trailering if you leave the cylinder pins in every time you hit a bump it pivots causing the cylinder ram to move and the hydraulic fluid has nowhere to go causing hydraulic shock. If it is not leaking fluid I wouldnt worry about it.
I too, had to get a mid-pto for $400-ish. I quoted a new one at like $8200 (but that would have been with the PTO). Pretty spendy. I kept track of what the trip cost me (gas was huge, hotels, food) and it was $1200, almost exactly. So, really, we're not even that far off. Mine was..........I dunno, 5 years ago. Dunno if that helps or hurts.
5th hose? I have 4. Some hydraulic chute motors have relief built in but they cost more others use a 5th hose (5 hydraulic hoses) for a relief which connects to the HST drain plug.
My seller was not mechanical either. He bought it new, and literally never used it. he let me take the brackets off his tractor. The way that went down, I had to leave too-long bolts in his tractor (showing/telling him, so his dealer could come out and fix them) and then I had to buy longer bolts than my tractor had. I forget which brackets that was for (thinking the middle ones), but it was a little extra pain. If I'd have known, I could have pulled my bolts to give to him and kept his bolts. aah well.
All things considered, it's amazing it worked out. we built a trust with each other. To the point that I drove 13+ hours from home and that he let me "wrench" on his tractor. Heck, he wasn't even home when we (I brought a buddy with) started. Cool guy. Everyone was happy.