The Norton Commando is one of the best British machines produced during the late 1960's through the mid 1970's. I owned a 1971 Commando briefly in the 1990's and soon regretted selling it. In 2018, I bought this 1973 850. It was in fairly good condition, though it needed carburetor and transmission work. Today, it is a strong runner and a keeper.
A few known problems the Commando suffers from:
1. The notorious original transmission layshaft ball bearing is known to come apart when the steel cage fails. This bearing will inevitably fail and possibly lock up the gearbox. Replacement with a high quality roller bearing is highly recommended.
2. The rear brake lever: If the brake cable fails, the long brake lever will pivot down and dig into the road surface catapulting the motorcycle and rider; a crash is likely to happen. It did happen to a fellow rider in the 1980's. A $9 aftermarket return spring is an easy fix.
Of all the motorcycles I have owned/ridden over the years, the Norton Commando is my favorite riding machine.