Return flow problem

[PoolDoc]

Your near return could be crushed, and still allow full flow to the far return, if the lines are separate -- check your piping at the filter pad -- OR if the near return line is crushed AFTER it tees of the main line.

[vinper]

watch the pressure gauge on filter when you plug the good return if the pressure rises there is a restriction in that line .. Have you taken the return jet off and looked in there , they just unscrew, try running a flexible fish tape in from the pool side while running could get lucky ... I assume there is only one return line leaving filter then splits up . or tee's off ?

You also could cut return line at filter, plug the good jet and try a wet vac to suck any obstruction back out . Or use a sump pump and tie it into the bad jet line and blow it back out ( house hose wont have enough pressure). Or the simplest would be to put a restrictor inside the good side to reduce flow there by balancing the two line's. restrictor as simple as cutting a 1/2" piece of the next smaller side of pvc pipe insert in behind good return jet. Just somethings I would try