Yesterday, we had it serviced and checked by a mobile mechanic. It runs great, and appears very well maintained for it's age (1988).
Here is a nice description that we found on www.weekendfreedommachines.com:
In 1984, Deere introduced the 430, Deere’s first tractor to combine a diesel engine with hydrostatic drive and power steering. The 430 utilized a Yanmar 3-cylinder water-cooled diesel, and all of the features previously found on a 420. Turning radius and attachments remained the same, but weight was up; 1170 pounds. The heaviest, strongest John Deere garden tractor ever. Many consider these to be the best that John Deere ever built, perhaps the best in the industry. No other garden tractor combined all of the features and stamina, convenience and versatility that epitomized the 400 series.
Impressive review. Hope this machine will give us a few more years of fun working in the vineyard !