perkins 30 hp compression

I have an older ASV RC 30, ive had it about 4 years. It has always started well as long as you glow it for 5 seconds, When hot, glow plugs arnt needed. Its got about 1400 hrs on it, doesnt burn a drop of oil, doesnt use up antifreeze, has enough power for what I do, which is snow clearing on my property, gravel for driveway, mud earth fill occassionally. Today I was clearing snow, and I could hear an annoying sqeaking at higher RPM, dies down when lower RPM, so I was checking around the rad area for something rubbing. thats were I could hear it. I was checking water pump bearing, when I realized I could turn the eng over relatively easy, with the fan blade, I would get to compression and it would be harder, but could still turn past compression with fan blade. Im no expert on Perkins, but i didnt think I would be able to do that. Do I need a rebuild, Does anyone know what compression should be, its the 31 hp 3 cyl. thanks in advance.