There are specialty hydraulic shops anywhere there are tractors, construction equipment, trucks, forklifts, etc. Possibly the nearest big city but in my case adjacent to a farm town of 10,000.
I paid $165 to have a cylinder resealed. I watched, it looked simple. So next time I went to HF and bought a 36" pipe wrench, added a cheater pipe on that, and disassembled the cylinder myself. $10 for seals total cost.
Pro tip: leave the cylinder attached while you loosen the end cap so you have something to pull against. And leave the opposite end attached when you unscrew the bolt at the tip of the internal piston rod.
This isn't complicated. Just be careful to not ding any precision surfaces.