Engine John Deere 425 oil Blow By

I recently purchased a 1997 John Deere 425 with the Kawasaki OHV engine. Hour meter shows 900+ hours. I have noticed what appears to be engine oil blowing by thru a plastic tube coming from up by the carburator. There isn't any smoke from the exhaust so I'm wondering if there is some valve in the upper engine that might be causing the engine oil to escape. I also would like to find a link to print out the JD425 electrical schematic. Thank you.