Rack and pinion has me stumped

I have a AMC pacer rack on my 37 chevy truck and lately I've noticed a strange problem that has me asking for help. When I drive my truck and turn left it works great, smooth like it should but when I turn right, the wheel doesn't want to come back and it takes alot of strength to turn it. When I have it in the garage with the motor running, I can turn the steering wheel both ways with no problem, but when its moving is when I have the problem. The rack is in good shape and hasn't lost and fluid, the truck has been aligned and tie rods and ball joints are ok.

First, make sure all the suspension attachment points are tight. Then, get it back on an alignment rack and double check the settings.

is it a power rack? if it is you mighe have air in the rack