Interior and Upholstery Power lumbar questions

I hope I do not already know the answers to this problem. When I had the seats recovered, I had the driver’s seat leaking lumbar bag (heavy rubber) replaced with a new Ford part with the same number (a plastic bag!) It did not work for very long. The pump still sounds like it is working, but nothing inflates. I plan on testing the pump’s output and seeing if the bag inflates from the line with a low psi air hose nozzle.
If it’s the new plastic air bag -
1. Is the HD black bag available new?
2. Should I try to patch the original bag with a tire/tube patch?
3. Do the top seat covers do not clip together at the bottom, Velcro or zip like my newer Fords, so there’s going to be sewing involved to get to this?

Thanks for the SN95 suggestion. As hard as the replacement bag was to find 5 years a ago, I was thinking I was at the last resort stage.
The other answers were exactly as I hoped or feared they would be.
As it snowed two weeks ago, I had the car parked off site, and could not look at the seat backs. I will get a pic and measurements of the stock bag and be back about this. We are still figuring out where stuff is after a move. I hope the part number is still readable.