I have a customer with a Richdel system that's about 10 years old. Several of the 4" 100 Series heads are not popping up enough to clear the grass, creating a coverage problem (she said it's been that way for 3 years!). There are a few like this in each zone. Usually, if I touch or push down on the pop-up riser it will come on out to full height. But, turn the zone off and back on again, and the same problem occurs. There is a little scaly buildup inside the heads, but cleaning this up makes very little difference. The internal head components look okay, the wiper seal is in good shape, and there is no obvious sticking or binding when pulled up manually (maybe a little rough). I tried replacing a few with Rainbird heads/nozzles, and those popped up fine. The customer is okay with replacing the sticking Richdel heads with Rainbird, if that'll solve the problem. I don't have a lot of experience with Richdel heads (only with their failed valves). My question: Should a 10 year old Richdel head be shot already? Low zone pressure could be the issue, but it doesn't seem like it would wait 7 years to show up.

Should I keep swapping out the heads?

Thanks. Van TX LI11462