Hi, from experience, it is common for these gears to have failed in the 730, 830, and 930 models. I think they are usually replaced by now if someone is using the machine. I am relying on my memory here so what I'm about to say is only as good as my memory; those original gears were prone to splitting due to the materials used (something about it wasn't quite the right chemistry.). And, the replacement gears that are being installed today are much less likely to have a problem. My expectation is that I will never have to replace mine again; nor will my daughter who has an old 830 mechanical that she adores. My OSMG replaced the gear in a 730 for me and I think the bill was about $70. I looked at a 930 once and that also had the cracked gear. For more information, please join the Yahoo Group called BerninaThirtySomething. The "Thirty" referring to all of those old mechanical machines: 730, 830, 930, 1030, etc...... Not the newer electronic models. There are some very knowledgeable folks in that group. You can't go wrong with an old mechanical Bernina even if you have to change a gear once - JMHO.