My singer machine has this issue where it stalls for a bit while I'm sewing and then continues sewing again. The motor is obviously trying to run as there's a brrrzzzttt kind of sound whenever the machine stops sewing, and I've also noticed a bit of a smell coming from it. I just started taking on my machines' cleaning, maintenance, and repair so I decided to look around my 15-91 and try to figure something out myself. I'm wondering if it's an issue with the grease cups and the grease wicks (I looked in there and it's pretty yucky), but I wanted to get outside opinions as to what my singer's problem is. All advice is much appreciated!