440B hydraulic issues

First off, thanks to Chris for helping with password retrieval.
I have a 440B powershift skidder. Last fall I replaced the charge pump with a used one. That's all I could find. It seems to be performing well, but the machine suddenly lost most of the hydraulic power the other day. After some troubleshooting, I changed filters, drained the transmission and cleaned the sump screen checked the filter relief valves and found the trans. filter relief was missing the spring guide and the valve is stuck up so not relieving. I order a new guide and sensor/plug. Not wanting to wait, I continued on and checked out the stroke control valve and reset the standby pressure. All is more or less normal again, the filter relief must have been stuck for a long time before I got the machine. I have three questions. One, the standby pressure is the same at idle as at the spec'd 2500rpm. Is this normal? On another post I read that the charge pressure can be checked at the lower 3/8 port on the stroke control housing. Can this be used as an alternate to the CLUTCH test port?
Blade function slows when steering so I will check out the pressure control valve today and then bleed the steering valve, warm her up and try again. I'm wondering about pump volume but don't have test equipment to check that. Any ideas or opinions on this?
I'm not a mechanic, but a logger and operator with tools and bush repair experience so I appreciate the expertise that many of you are willing to share.

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If that stroke port has a clear and unrestricted path back to the trans charge pump circuit without any check valves/relief valves/divert valves in the way. Then yes it's not pretty but it's ok.

Standby pressure is always supposed to be 2250-2500psi from idle to redline as long as flow demands don't exceed pump capacity. Weithe rit be zero flow standby or operating a function.

Oil is going to flow to the path of least restriction/back pressure. If it's easier to push the steering cylinder than lift the blade or spin the winch under load. Then the blade or winch will slow or even stop.

Good catch on the transmission valving. Most people change the filters, change the front pump, maybe change change the trans pump. Then baffled, they trade the machine to the next owner.
Most people seem more ready to pull perfectly fine main pump out and replace them for nothing. Rather than connect a pressure gauge and do a little thinking.

Thanks for your reply. I wasn't sure about the standby at idle but it makes sense. The pressure control valve on this model gives priority pressure to steering and brakes and the winch controls are powered with a pto driven onboard pump, unlike the C model which gets it's hydraulics from the main pump. I was going to take the PC valve apart for inspection but I decided to bleed the steering valve first and that provided a great improvement. I guess I rarely use full turning and full blade lift at the same time when I'm working so results seemed odd as a diagnostic. Back to logging in the morning.

You must be getting some winter up there by now?

Minus 35C this morning, thats 30 below on the F scale. We have about a foot of snow accumulated in the bush. We have come to expect lows a little above zero on the F scale this time of year, but Pacific Decadal Oscillation is just entering a 30 year cold phase. This will likely see us return to the colder winters of the 50's, 60's and early 70's.

And I was feeling chilled at 25F. Then again it's very humid here beside the lake and 15+mph wind is normal. I've heard people from Thunderbay complain how cold it is here.