Paramount PCC infloor cleaner insufficient pressure

Hi-

I just moved into a new house with a pool that has the PCc-2000 system installed. The new water modules I installed (4 port and 6 port) seem to be working correctly, however, they only see about 9-10 psi of pressure (as opposed to the 14-24 recommended. If the nozzles are original any ideas what could be causing this? I have several dead corners of the pool that accumulate sand and debris that are a bit frustrating considering the 99% clean guarantee the Paramount advertizes. There are also 2 zones that seem to run a shorter cycle than the remaining 8 zones, any idea on this? Potentially important info: 420 sf cartridge filter, 2.5 hp pump with 2" piping, 22 psi on filter when clean.

Thanks,
Milan