Is it the old style that mounted on the T bars or the shower type? If it is thr shower type try to take the feed line off of the distrubution block and see if you have pleanty of feed. If not change the injector and if you have pleanty of feed take apart the foam head and change out the scrunchy pad.
Yes there are a newer style that mount on the bridge and are much smaller than the older tube style manifolds.
If your tube manifods are plugging up try switching colors, switch incoming hoses on the chemical lines and see if the problem moves or stays with the manifold this will point you towards the injector or manifold problem.
Any questions please feel free to call me.