Just make sure the wobble drive is tight. If he is hard on stuff it may not have been greased like it should have been. Also look at the drive sheave on the hex shaft. I've seen those get loose on the shaft. Those sheaves were like 80-90 dollars when I was selling them. I think they are 300-400 hundred now. It's held on with a nut. The 1020 was improved on where the knife bolts on vs the 820. That didn't give much trouble. Good luck
My dad went to the country school 1 mile east of my place. He would have graduated from 8th grade in 1954 or 1955. He said the country schools gave the best education. The 1st graders learned what the 8th graders were being taught and the 8th graders got a review when the 1st graders were being taught. The students also were part of the school's work. Brought in the firewood. Filled the water cooler. Helped the teacher clean up. Most importantly were taught the three R's. Dad's school house got moved to town and is now a house.
The John Deere's 9000's are wider because of the cylinder. I used to have a 6620 and before buying a 1660 looked at a 9500. Couldn't believe how wide it was. A lot of my customers years ago had 4 row heads on 40/60's.
Buy a 40/60. I've been out of the dealership parts since 2008 and some parts were NLA back then. And very little aftermarket support for them. Good 40/60's are only bringing 2000.00 to 3000.00
I sold SCH, Crary and the 3" conversion kits CIH offered. I always told the customer WHATEVER they bought to replace the 1.5" quickcut would be an improvement. Another important part when converting from the 1.5" cut was to change the drive pulley.
1020 for the skids alone. Those large 820 skids held a lot of weight in dirt. I sold lots of AHHC kits back in the day to use a 1020 on and older 1400 series. A least in our area most 820's were 15' A 20' 820 if around is probably worn out.
From what I read thru the years, the N7 was an awesome capacity machine in its day. From what I also read they came with a free Patsy Cline tape. "I fall to pieces"
The Deere engines I pulled: 4400 diesel 329. 6600 gear drive 359. 6600 hydro 404. 6620 hydro 6466T. There defiantly could have been variants. But that's what I ran into. Of all those engines, the 404's sold best.
A neighbor years ago custom combined with two 8820's. I think a non-turbo 6620 was usually a gear drive.. With the old 6600's a gear drive usually had a 359 and hydro was a 404. That's what I observed. I used to get calls from our local scrap yard when they got a combine in. I would buy and pull the engine. Pulled a lot of IH and Deere engines. Even a few 3208's out of New Hollands. That ended a number of years ago when they got a new manager. No more selling out of the yard. Shame.