Kawasaki FX850V-BS13 oil pressure problem

[SUKI]

I am working on Kawasaki FX850-BS13 with 3000+ hrs on it. It having low oil pressure indications. The measure pressure is 39 psi cold and 15 psi hot. Service specs 43 psi minimum. I have found several items at near minimum specs in the oil pump area. I do have a couple questions that the service manuals don't answer.

Anyone that regularly service this engine might be able answer the following. I hope. I got a call in to the local JD dealer service department but don't much confidence in them as they couldn't even find a bad spark plug recently.

1. Does the oil pressure oil relief spring needs some pressure on it? Current measure just above minimum spec'd free length but sits in place loose.
2. What is the relief hole maximum depth?

Neither of the these questions is address by either the Z950R or the FX850V service manuals.

Also note the oil pressure switch is new but is appears to switching at around 15 psi instead of the 4-6 psi the service manual specs.