MF245 lift problem

[halwest]

I have a Massey Ferguson 245 orchard model, Perkins 3 cyl. diesel, power steering, dual remote hydraulics. Purchased used. First thing I did was change all fluids and filters. Recently the rear lift will only raise when the tractor is running at a low (less than 500 RPM) If RPMs are increased the lift arms will lower. As the engine warms up I am able to increase the RPM's and the lift will work. Once everything is fully warmed up it appears to work normally. Through all this the auxiliary hydraulics
work normally. If I shut off the engine with an implement (5' finish mower) in a raised position the implement will stay in the raised position. Based on the casting # on the lift cover, the system is not pressure controlled. I have both the service manual and the operator's manual and can find nothing on this specific problem. Any help / thoughts on this would be greatly appreciated.

 

[halwest]

OOPS!. Tractor may or may not be pressure controlled. Not sure how to check. Meant to say tractor does not have a dash pot.

 

[Rock Crawler]

Just a heads up: Double posting is frowned upon within a forum. It muddies the responses and typically causes you get less help.

2nd post of same question: http://www.tractorbynet.com/forums/massey-ferguson-owning-operating/385179-mf245-3-pt-lift-problem.html#post4861942