Oh sorry, I managed to mix this up with another post. The 731 should be very close to my 730, two drivebelts, for the motor and a timing belt. The occilating hook is nice, very even zigzaging on this model. All 730 and close numbers like 731 aren't exactly the same, but generally the cam gear function under the top cover is. The first thing to check is this gear (easy to do), and do a general clean and inspection of the gears, under the top of the machine, and under the top of the freearm. There is a cover on the side of the hand wheel that needs to come off for the drive belts. The clutch wheel is not a bad thing to check either, but not the most common issue.