Gummy Case


Hey folks, I'm going to coin a new phrase here...Gummy Case Disease. I just picked up a nice 34c, but when I took it out of it's stock HP case, it was covered with disintegrated, somewhat gummy feeling foam particles, from the lining of the case. Has this ever happened to anybody else? My woodstock (29c) has a plush beautiful FUR LINED case...I guess the bean counters got to 'em and made them go cheap on the cases after that!!

Regards, Hal


Hello Hal:

Yes, I've experienced the same phenomena with an old 41c case.



Throw it (the case - not the calc!) in the washing machine next time you do laundry. Some people turn them inside out. I did mine "warm wash, cold rinse" with detergent in my work clothes, no probs.

I think the breakdown of the foam can be overlooked. Remember: HP didn't think that they were building these things for the ages. They just thought it needed to last, albeit flawlessly, till the next model came out. Then - successive models just got better.

Edited: 9 Nov 2005, 12:29 a.m.


The washing I've heard everything. But hey, I'll give it a try.
Thanks much for the tip.


But DONT use the dryer. Just prop open the case and let it air dry. Comes out looking like new.


My oldest HP calculators (a 34C I recently bought on eBay, and the 15C and 16C I bought new) have cases suffering from Gummy Case Disease. I don't have a 29C (although I drool at the thought of having one) to compare it to, but my TI SR-56 (circa 1977) has a plush fur-lined case that shows no degradation.

My first thought was to get those calculators out of the diseased cases. The 34C is currently wrapped in a white handkerchief in its storage box. For the Voyager calculators, I called HP support, figuring that they would still sell replacement cases since they still sold the 12C, but I was wrong! The did refer me to CalcPro and Samson Cables. I called up CalcPro and told them my case needs. They said they would get back to me, but never did. I found a reference in this forum to someone in the UK who sold HP cases, but I decided to find something domestically. I searched on eBay and found Voyager series cases made by Ann at the Corner Store (eBay ID annstcs) and they are really nice! I told her that I needed a case for a Pioneer series calculator that didn't have one. She added those to her slip case product line and sent me one. She's even considering making me a case for my 34C and I just emailed her tonight to tell her that I just received a 35 with no case (I bought "Old Trusty" on eBay).

I'll try washing those cases as suggested. Also, I guess I better check my 41CX case! Does anyone know how to safely clean the keyboards to get the black gummy particles off?



A UK store that still sells some "Genuine HP" cases is Classic Calculators.

I bought a hand-made genuine leather case for my 16C from Ann (annstcs) on eBay, and I'm very pleased with it. Note that she sells both genuine leather and (lower cost) felt-lined imitation-leather vinyl cases. If you don't see the style and color you want, I suggest sending her an e-mail asking about it. The last time I checked, she had a couple of ads for her eBay items in the MoHPC classified section.


Edited: 9 Nov 2005, 3:13 a.m.



See for her current items.



This happened to some Spice here, but never to the 41 cases (or others), these are of better quality. As I am reluctant to put cases in the washing machine, the calculators are put into a clear plastic bag and bask into the case. Maybe the plastic bag can stick to the machine or alter the colors eventually, but this hasn't happened (yet ?). Has anyone experienced such problems ?


I have the same problem with an HP-41 case. Has any one already tried the washing machine solution with these ?


I have had several "gummy" 41 cases. The washing machine solution worked fine for me.


I did it with several 41 cases. The goo is gone now.



Brush off the particles with a tooth brush. Then fold up a paper towl and wet the edge with Windex window cleaner. Wipe your miseries away...

Possibly Related Threads...
Thread Author Replies Views Last Post
  Gummy wheels for 41 series card readers William L. Drylie 5 555 08-30-2011, 11:26 AM
Last Post: William L. Drylie
  HP-97 Card Reader NOT gummy wheel problem ZOleg 3 482 02-03-2009, 07:12 PM
Last Post: ZOleg
  HP-41 Card Reader NOT gummy wheel problem Rich Forest 19 1,546 01-12-2009, 10:59 AM
Last Post: Ignazio Cara (Italy)
  HP-67 Gummy Roller Successfully Repaired Grant Henson 6 673 12-19-2006, 07:10 PM
Last Post: Grant Henson
  Gummy Wheel Fix Peter Hendy 4 447 03-07-2006, 10:23 AM
Last Post: David Smith
  Gummy wheel repair , Need O=-ring size Frederick Harvie 6 756 11-05-2005, 04:58 AM
Last Post: James F. Chumbley
  7470a plotter gummy wheel question Andy 2 338 10-29-2004, 07:41 PM
Last Post: James
  HP-65 Card Reader "Gummy Wheel Problem" Dr. Carl P. Loller 6 607 02-18-2004, 03:57 PM
Last Post: Dr. Carl Loller
  'Gummy wheel' Phil Jonker 2 354 10-24-2003, 09:48 AM
Last Post: Juergen
  HP 85 gummy wheel repair hugh steers 15 1,170 06-03-2003, 06:59 PM
Last Post: hugh steers

Forum Jump: