Do not force the dials, or they could break. I have resurrected some older Berninas whose knobs were totally frozen. The dials usually get stiff when the oil is drying out. Be sure you are cleaning and oiling your Bernina 830 on a regular basis. Use only NEW good quality oil (not 3-in-1, WD-40, or cooking oil). Only one or two drops in each spot per your manual. To help loosen things, direct hot air from a handheld hairdryer into the interior of the machine (direct it toward the buttonhole mechanism). See if that helps loosen things. You should perform regular maintenance on your machine every 40 hours of use or every six months if not in use.
If the dial is still sticky, slowly rotate the dial and study how the mechanics work in the machine and apply a drop or two of oil to the places where metal rubs against metal.
Hope this helps.
Carol--glad you were able to get it operating again. Using +40 yr old oil is probably not the best choice. If the oil is dark yellow or brown, you should discard it as it will eventually become gunky too. You can pick up a fresh bottle from a Bernina dealer--be sure to tell them that you have an oldie (but goodie) Bernina 830 Record to get the correct oil. You can get the dispenser with the long spout to get into hard-to-reach spots. There are other oils you can use (can't remember the specs right now), so unless you want to do some research, Bernina oil will do just fine. (You can join the Yahoo Group for BerninaThirtySomethings where there is a ton of suggestions on oiling, operating, maintaining, and using your wonderful 30-Something vintage machine. There is also a long conversation about types of oil to use.)
If it seems your machine is kind of sticky (difficult to turn the handwheel, or the motor seems to strain to get things moving, etc.), then a good suggestion is to put a drop of oil on every moving metal-to-metal joint. (Slowly rotate the handwheel, the dials, and levers and watch where things move.) Do NOT oil the two plastic gears or the metal cams!!! And, use only 1-2 drops of oil. Be sure to get the 4 or 5 oil holes on the needle take-up mechanism (they look like rotating knuckles) and adding a drop where the needle bar rubs would help. Look for a couple of other oil holes just to the right of the cams that help keep the stitch selector operating, and don't skip the oil hole on the right near the handwheel. Be sure to get the oil holes in the bobbin area (there's usually one on the far back behind the bobbin mechanism next to the case that is difficult to see, and also one on the far right that helps the feed dogs. Once you've hit all the moving joints, you can hand rotate the handwheel to get things distributed. Then try sewing slowly. You should notice your machine runs much quieter and smoother now. Such a happy sound!!!
Once things are moving well, you probably won't need to oil the individual moving joints again unless you notice things are getting a bit sticky again. Too much oil is not a good thing too, so don't over-oil!!!
Cleaning the bobbin area and putting a drop of oil in each oil hole and the hook race is probably sufficient to keep your machine regularly maintained. (The manual does not show all the oil holes, so you might have to look for them. Once you are able to recognize them, they are relatively easy to locate --be sure to rotate the handwheel as some oil holes are not always visible.) Some machines have a red dot to help you locate the oil holes, but sometimes not all of them are marked. (The picture below will help you locate the oiling spots.)
Be sure to run your sewing machine on some scrap fabric after oiling to make sure you don't stain your nice project!
Enjoy your lovely machine! Treat her well (oiling and cleaning), and she will treat you well for many years!