HP-97 Printer Motor keeps spinning


I have an HP-97 and I was trying to see why my printer was not advancing the paper when i started to hear a humming noise. The noise turned out to be the printer motor spinning. Now, when the calculator is turned on the printer motor keeps spinning. Does anyone know how to fix this? I have not checked the paper advance switch wires to see if one of them has broken (disconnected). Thanks


The idler gear has stripped. You can make a replacement: HP-97 Printer Gear Replacement


Randy is correct, and Katie's article is excellent.

Both my HP 91 and HP 97 have benefitted from this repair.

Cheers, Geoff

P.S. I tried to find the gear at Small Parts website and was unable to, try emailing them directly with your request:

- 80 pitch
- 30 teeth
- 1/8" gear face
- 3/8" hub diameter
- 3/16" hub projection
- 1/8" bore
- made of aluminum, acetate, plastic

Cheers, Geoff


I've also bought replacement gears for my 97s from that unmentionable website. I haven't seen any replacement gears for sale lately but the seller does pop up periodically.



His name is Dave Bowman, and he no longer sells on ebay. However, you can still contact him via ebay messaging at DAVEHAL2001. Last time I checked with him, he still had some printer gears which he was willing to sell direct.


Small Parts does not sell gears, PIC Design is the source.

If you can get a gear from Dave, even at $25, they are a bargain and a better fit than making your own. Been there, done both. Buy the custom part from Dave if possible.


Ordered the gear from Mr Bowman. Received it earlier this week and installed it today. Printer works great. Thanks to everyone for their help.

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