so.. what's this on.. sherman tank? Boeing 747?
i'm guessing 9-2-8n by the sound.. but the 8n uses a different control mechanism than the 9n/2n.. so some advice will be different. I'd rather not type in the entire deal and then you tell me it's the other machine, since i type on a mobile device.
When you reaced in.. if you were able to move a control fork or rod and rocker to get lift arm movement.. it sound slike sticky control valve and dirty oil.. what decade was the sump last cleaned and oil changed?