Earlier this summer I installed 15 RB 5004's in my backyard. So far I have replaced one because it stopped rotating and another because the wiper seal failed. This morning I noticed another one leaking at the wiper seal. Am I just having bad luck or are there problems with these heads? Also, to avoid having to dig out the latest problem head and replace it, I would rather just pull out the guts and fix or replace the seal...is that possible?