A quick revival here to pass along a pleasant surprise. I've had a very nice Topeak Joe Blow Sprint floor pump for about 10 years. In the past few months it has gotten weak, taking 4 or 5 strokes to get up any pressure so I can top up a tire. Not good. Sure seemed like the piston was not pistin. I pulled the rod and cleaned the end and the o-ring and the cylinder walls. No improvement so I measured the main o-ring (expecting some proprietary metric size I'd need to buy by the hundreds from some UK plumbing jobber). "Gee, this looks like a bog simple standard o-ring, 1 1/8" OD, 1/8" wall".
And the Ace HW had it in stock for $0.59. I put that into the pump and we have a full recovery. Sometimes things go as you hope they will.