Sorry, for some reason I jumped to the conclusion it was about a 301, and I can't correct it by now, but the groups.io is still a good place to find advanced technical advice, and I personally still go for flushing out old grease and grime when possible. As you well know, with this model you have to take care and not get anything on the timing belt. A 306 is one of those models that respond very well to repated applications of oil, grease, moving all levers, knobs and a bit of test sewing.
Last edited by Mickey2; 10-19-2020 at 01:21 PM.