time to dust off my Nemo I think.. 

These are an exact match. Really hard to find 7.5mm in the US.

https://www.amazon.com/gp/product/B0824W72GS/ref=ox_sc_act_title_1?smid=A1THAZDOWP300U&th=1

uxcell Precision Balls 7.5mm Solid Chrome Steel G10 for Ball Bearing Keychain Wheel 20pcs

Thanks for the photos, just to confirm I measured the chrome bearing balls of the Nemo at 7.5mm diameter - I would think that 8mm balls would work ok but the distance between the faceplace and pcb may need a minor adjustment, I would be interested to know if thats the case if you try out 8mm balls.

I remember downloading your photographs of the Octopus..... re-attached.

Best,

Jean

i have seen this rust on a few of the genoqs over the years but not a lot, i am guessing it would have to do with the environment it was kept and the use of the unit.  seems to me like the ones that end up with rust are put up dirty for a long while. although this is just an educated guess based on reading auctions and talking to different owners over the past 15 years. 

i took apart an octopus long ago and posted some photos to the yahoo user group but they were of poor quality and i believe deleted in the yahoo group purge. i do not remember having to pry apart the octopus in order for the balls to be removed.  that was a first generation, so i am unsure if any mechanical changes were made over the years. i hope to find another octopus soon as i would like to revisit it as well. been looking online but havent found any recently.  unfortunately i missed one last year that had broken encoders, which would have been perfect for me because i take apart gear, clean it, mod it, upgrade it, take photos etc all the time.

Thanks for sharing. I'm interested in replacing the bearings on my Octopus. I bought it ~10 years ago on the cheap because some of the balls had some rust, no idea what the previous owner was doing. The button actuators work just fine and I'm wondering if plastic will be better as long as I don't roll them. In general, even though it feels nice to roll the balls, get it out of your system because they slowly wear the metal (and I'm sure it will be worse with plastic).

The big issue that I've run into is that the Octopus has a two layer metal panel and I'm not sure if it is held by glue or some kind of weld. I haven't been inclined yet to stick a screw driver in to try and pry the layers apart. Anyone have any insight on that?

i will share more information in the coming days/weeks. 

the ball bearings appear to be around 8mm to 5/16" and should be pretty easy to get. i put these on my simple cheap micrometer but will take them to the machine shop next week to confirm.  i have also placed an order for these https://www.mcmaster.com/plastic-bearing-balls/ in 5/16 to see if they work. i was trying to source some clear ones to see if i could get the led to bleed into the "step ball" as well. just playing around with some ideas for some stuff i am working on. 

the disassemble is super easy. the main thing you have to remember it to just put the units upside down and elevated off the table by wood strips, or as you can see in my photo i used 3 ring binders. there is not really anything else you need to know. once you have the pictures you just remove the screws and clean it up then look at the pics to put it back together properly. 

if anyone has any further questions or comments def post here, i love talking about gear.

below is the edited part of the longer explanation of why i took it apart and some other plans i have. 

i will for sure post more information here. i am doing a full tear down and cleanup, and rebuild, i may even replace the encoders while i am in here as long as i can source the proper ones.  i actually am a manufacturer and have been going through a lot of the sequencers(inside and out) the past few years to try and make something. i originally tried to clone the octopus/nemo but after really getting inside the functions and code i decided that i wanted to do things different so i am still pursuing that. if any of you OS peeps want to chat at length with me about stuff i am still in pre production on the eventual units i plan to make and would be open to discussions.  

that being said specifically for the nemo i am working with a wood cnc friend of mine to make new wooden rings for the nemo that will be made out of real wood and be stained instead of having that rubber on them.  he owes me a lot of favors so he is going to make me one and i may put a few others up online(reverb or ebay) for others that may be interested.  he started on it yesterday when i was able to give him the "ring" so i figure he should have something put together in 6-8 weeks.