The pressure should be much closer to 43 psi with or without the vacuum attached. The Reg is working, its just the pump is unable to produce the pressure. So either the pump is the issue or there is a restriction between tank and the pump
Use a handheld Tach, and connect to the input lead (which is a gray wire) on the Tach to see if you get a reading when the motor is running.
If you get a reading then check connections on the gauge and if good, you need a new gauge
If there is no reading then trace the gray wire back to the...
Reg 861126A1 is 43 psi
Connect air to the inlet with a gauge and regulator. Slowly increase the air and at 43 psi it should be wide open. If not its bad
What is your serial number?
I don't see the nut on the end of the pump as removable
Inland slip with walkway on both sides I use 4 lines and no fenders. Boat stays in the middle
Inland slip with only one walkway, 2 to 3 lines to maintain position, and enough fenders to keep hull off dock. After securing, rock and move the boat to see if you can get it to touch
Tie to AFT...
With everything replaced including the pickup tube, it has to be the new pump. That is unless there is a fitting which is clogged.
When the pump was replaced, you didn't happen to replaced the pump rod which rides on the cam? Hope not
I have yet to see "and would like to see" what the shift foot looks like when its fully locked in forward gear.
Is it dead nuts straight forward or off to one side
Great pic of the foot showing when its in reverse, but no pic of when its in forward. The reverse looks like its one tooth off, as in going to far (why it needs to be pushed wih your finger)
Plug, drive vent plug
The plug on the top section of the drive which is removed when the drive is being filled
Put your fingers inside the gimble bearing and rotate it. See if it feels a smooth as silk with no roughness
I would say it was not, or something was damaged when putting together.
Disconnect the cable at the shift plate and see if the cable can be moved until the prop locks in the CCW direction. Then look at the shift foot and see if its facing straight forward