That cyl looks like a Garrison Cyl
Welded design.....that repair shop should have cut it open and resealed it right (possibly it needs a new rod also)
testing any repaired hyd cyl with only air pressure is poor workmanship, unacceptable in today's repair world.....it should have been tested using hyd pressure test machine (usually min 1000# on that type cyl).....any more and it will rupture the internal cyl barrel
the reasons for premature failure from a bad repair is either bad fit, finish or poor seal matchup......in order to properly measure wear in that cyl it is necessary to cut it apart on a lathe, then measure, clean, polish, reweld, then repack the rod gland then test
They more than likely just pulled out the snap ring and replaced the wiper, oring and backup under the retainer washer only......Not what I would call a thorough rebuilt
$800 would be worth researching a better shop to do it with a guarantee