According to the spec sheets it is suppose to work at
pressures as low as 77 psi (I found different specs/sheets
too). Do they make any changes to the unit for the lower
pressure? I looked over the parts list and I couldn't spot
anything different relating to this. If something could be
changed for lower pressure operation now would be the time
to do it. Dependability would be a worthy trade off I would
think...

The only way to lower the inlet pressure requirement is to use a small gun
and low flow. You need 70 psi at the gun, easy if you're not pushing a lot
of water. I'm pushing 150 GPM, just a bit over the rated capacity of the
unit. This gives a lot of pressure loss in the reel hose. To get 70 at the
gun, I need 110 at the inlet.

Karl