CB 1400 oil pressure adjustment screw

[mra400ex]

Hello,
New to the forum and have an issue with my 1990ish CB1400.  Over the years I have maintained the heater.  I have an issue with the oil pressure adjustment.  I have noticed that the screw for it has had less and less adjustment and is lower than the air screw.  It has gotten to the point now where there is no adjustment to get set the pressure at the 2 psi.  The oil pressure from the pump is good and there is no restriction at the filter.  I assume that the diaphragm in the oil pressure regulator needs replaced, but ran across this site and joined.  Looks like lots of good info here.
Anyone have any thoughts on this.
Thanks

[ShopSpecialties]

When was the last time a burner rebuild was done ?

[mra400ex]

I have never had an issue with the burner or a rebuild.  I have replaced the Carlin transformer once.  The oil adjustment has gotten shorter over time and has no more threads left to adjust pressure with.

[ShopSpecialties]

Burner rebuilds are normal heater maintenance that Clean Burn recommends every year along with a service kit. I say every 2-3 years is plenty good and sometimes you can go longer. Over time the preheat block will sludge up and bake especially if the power is left on all year. So if you were a customer of mine the first thing I would do is a burner rebuild and install a service kit.