http://groups.yahoo.com/group/viking...chinespre1980/
This is Bill Holman's Vintage Viking Yahoo group. In the files section, he has a document decribing the fix for the "Viking stuck in reverse" problem. I would say that if your machine was serviced a year ago and has this problem now, it was not serviced correctly. I've had two 6000-series Vikings overhauled ($189 plus parts) and the tech removed, steam cleaned and rebuilt the pattern mechanism to remove the old oil that had it stuck. I had got both of them for nothing (one was $5, one was free) because of the cracked camstack and maintenance issues.
On the other hand both are great machines now (My SIL has one of them) and will sew just about anything with that low gear!