I have two Groco HF heads that have seen nearly 17 years of use. I looked into
other heads, but finally just did a complete pump replacement for the HFs. They
have worked well, only needing a rebuild every year or two. Have you checked
your discharge lines for clogging?
Jerry wrote:

Been using Grocco HF heads for a number of years only because, at 13.5
inches, they are the lowest height head I can find in any of the
catalogs. However, I'm getting pretty tired of the poor performance,
breakdowns and frequent repairs needed on these units.

In my boat the head sits on a shelf that is already 8.5 inches above the
floor which then slopes down even more toward the midline of the boat.
Even a 1 inch taller head is uncomfortable for this crew of short
legged people.

Anybody know of a low rise head model that is 13 inches high or less?