The 800 series didn't have holes in the
original bobbins, flat sides with only a tiny square cut out near the "hub" (or center) of it. I have a 730 Record (1965 perhaps a year or two later), and a 900 Nova (ca 1977), they have been used a lot and still run fine. They came with identical bobbins as the 830 and 831. They've been in for service about twice in their life, and have never been high maintanance in any way. The 730 had a pedal issue early in it's life (before I had it) but have been running fine since.