Unscrew each nozzle, there is a check valve ball and spring underneath.  I soaked them in acetone and replaced.  Then, after reassembly I pumped acetone thru the pump (got out some sticky black stuff).  Finally I replaced the reservoirs.  Works great now.  Don’t forget to weigh a couple of pumps to make sure it is dispensing the correct ratio.  Throw this initial test batch away in case it is contaminated with acetone.  I don’t think acetone will affect the reservoirs, unless they have changed the material.

Bob

Lancair 56SH