I have a 6020 I got in a thrift store for $5.00 because I showed the manager the cracked cam inside and told her it needed $250 in repairs. It had been left by the front door with a note that said "needs work". It came with the foot control, manual, standard foot and A cam. I have managed to find all the rest of the accessories. I know an OSMG Viking guru about an hour from me and he rebuilt it. Well worth it and it is a workhorse. I don't know any other domestic machines that have the low gear. My hubby uses this machine to make a lot of canvas gear for his black powder shooting hobby.
I now have another, my hubby found a 6030 at the same thrift store for $10 but it had most of the accessories, and I thought I could sell them and give the machine to my guru for parts because it was frozen. He convinced me it was a good repairable machine and he was right, except now I need to sell it to recoup my investment.