Greetings, Trackballs.EU Family:
I recently purchased a Kensington Pro Fit Ergo to play around with in my home office, to give my wrist a break between using my Expert Wireless - I've come back to trackballs after years on a vertical mouse, and the Pro Fit Ergo has an incredibly comfortable shape, despite being a thumb tracker.
As of this date, the Pro Fit is $74 new on Amazon - I bought an Amazon "renewed" version for just $34 (didn't want to risk tearing apart a new one and breaking it). Amazon stated it was in "Acceptable" condition, but upon receiving the unit, it was in brand new, untouched condition in all original packaging, so I guess I got lucky there.
Before going into the teardown and upgrades, here is a list of the parts I used for this project:
Kailh Black GM8 Mouse Switches:
https://www.amazon.com/Kailh-Mouse-Swit ... B08ZN1N1S9
Uxcell 2.5mm Chrome Steel Bearings:
https://www.amazon.com/gp/product/B099949ZRT
Perixx 34mm Glossy Black Replacement Trackball:
https://www.amazon.com/gp/product/B08DD6GQRV/
Lanolin Oil:
https://www.amazon.com/gp/product/B07GX6CTV4/
Step 1: Disassembling the trackball
I generally followed a Korean teardown guide here, which I highly recommend referencing also: https://www.youtube.com/watch?v=YOe1y8O9Tuo&t=672s
I started by removing the sticky adhesive pads on the bottom of the trackball, peeling them off carefully with a "slim" guitar pick (a plastic spudger is more recommended if you have one), and then removing them with fingers - you just have to remove all but the right side pad. This reveals several "Y" screws that require a "Y0" sized screwdriver. I recommend not trying to force the screws with a flathead or Phillips head as these screws are cheap, metal-in-plastic, and can strip easily. I bought my Y0 screwdriver locally, but you can order the same driver from Amazon for less than $10.
After removing all of the screws, use a plastic spudger or guitar pick to gently work your way into the seam of the trackball - that mates the top cover to the foundation, starting from the top right corner of the ball, under the buttons. Again, refer to the aforementioned teardown video on YouTube for a visual explanation.
Once inside of the trackball, you have to gently release several retention clips to release two ribbon cables - be VERY gentle and CAREFUL with these - they snap and break easily.
Once the ribbon cables are detached, the trackball cup and the daughterboard of the button switches can be released - these are simple phillips head screws. Again, remove them carefully as we're dealing with cheap metal screws driven into plastic.
Step 2: Modifications
Starting with the trackball cup, I noted the locations of the stock synthetic ruby bearings, then measured where I would need to drill directly behind them. Using a 1.0mm drill bit, and making pilot holes every time before starting, I drilled into each receptacle holding the stock bearings (there are three) - which popped out the bearings from the other side. I then merely took my replacement steel bearings and popped them into the receptacles, pressing down firmly with a small flathead screwdriver. Please note that if you drill into the receptacles using a larger drill bit, you may make a hole too large where the bearings will fall through the cup - which will then require you to plastic-weld or seal off the holes you made after installing the bearings. This is really not ideal, so I recommend sticking with a 1.0 or 1.5 bit for this mod.
Replacing the left and right mouse buttons was far more tricky. The factory solder job isn't the best, and there was flux everywhere. Also, it appeared that the stock switches were soldered from the TOP of the board AND on the bottom.
I therefore desoldered the bottom pins first using a solder sucker tool and also a soldering wick to mop up the excess. I also broke apart the stock switches with needlenose pliers from the top, revealing their pins, which made it easier to remove (gently pulling them while applying the soldering iron from the bottom side of the board).
Once the stock switches and their pins were removed, I also cleaned up the holes more with the iron and solder sucker. Once this was done, soldering the new switches to the board was straightforward - the top two pins required soldering and the bottom one did not. Make sure that the new switches are FLUSH and SEATED flat to the board before soldering - or else you will have to re-solder and re-seat which is a huge pain (I had to do it with one of the switches where I wasn't paying attention).
Step 3: Reassembly
Reattach the daughterboard for the switches, and the trackball cup using their respective screws, and re-attached the two ribbon cables - again, make sure they're facing the CORRECT way and GENTLY secure them with the plastic retention clips. Then, reassemble the plastic housing in reverse order - everything snaps in with plastic clips to the bottom platform, and is further secured with factory adhesive. Replace the bottom rubber pads - the stock adhesive should still work without requiring re-gluing.
The Bottom Line:
I lubed the Perixx 34mm replacement ball with Lanolin oil, and polished it. The action on the new steel bearings is indeed smoother than stock and a bit more quiet when aggressively flicking the ball. Although I wouldn't say the stock action was horrible/unusable with the original ruby bearings and ball, I'm able to make much more precise and fine movements now after the modifications.
The Kailh Black switches also feel different from stock. There is more tactility, and a slightly firmer "click" with a positive sound similar to high end Razer gaming mice. Moreover, the switches are rated to last millions of clicks, which is probably more than the stock switches that Kensington used (they looked generic Chinese OEM to me).
I hope this helps those of you out there who are looking for an ergonomic trackball to use, and would like to upgrade it into a more premium product without breaking the bank.
Pictures:
