Hi Mike
Check your pump diaphram/gasket and the o-rings on the pump and head. Next , Then resurface the valve cover on a glass plate with 800 wet sand paper, to make sure it`s perfectly flat.
Depending on the engine version , the pump adjustment housing and the faceplate on the pump valve housing will have irregularities causing the diaphram to either get cut over time and leak, or the o-rings are not seated good in the head

Also inspect the hattari O-ring , make sure it`s an original Hattari. All others I`ve tried are not sized correctly and leak under pressure.
This is most likely the problem if both motors are doing it.

These are the most common leak problems.

Bryan