Knew guy to TBN. So after a lot of research on jd garden tractors I settled on a older model 420. They seem to built like a little tank versus the newer ones. After looking for a nice one for awhile finally found one close to home in nice condition and for what I was willing to pay. Only down fall is it has about 1700 hours on it. It has the 20 hp onan and a 60 inch deck under it. Have noticed that the valves sound noisy and was wandering if there was any adjustment on them. I have had a couple other models that have had the liquid cooled Kawasaki in them and the valves where easy to adjust but the onan is different. The previous owner said that the engin had been rebuilt and from what I can tell he was being truthful but how competent the person was who did the work is anyone's guess. Has anyone ran into this issue before I know that the onan was used in a lot of models back then. Any help would be great. Thanks.