I too run a Shoebox, had it for about 10 years. Got a backup as well, plus a boneyard one for parts.
Topping off two large tanks every week. I also have the Brancato high-pressure filter between the Box and the bottle, plus a three-filter set-up on the low-pressure side feeding the Box.
I kept track of hours in a notebook on my phone for about 5 years. Kept notes previous to that. I have rebuilt twice on both, one was a 'ground up' rebuild from a nice used Box bought from a member on this forum.
I missed buying from Tom but located Zack at OCO Labs (Tom's new endeavor) for some of the parts that still work on the Box. Other parts I watch for. Really the only parts that don't seem attainable from say McMaster-Carr, are the cylinders, main block, support rod and piston spacers, which I assume are all custom parts. I have a line on most other parts from various vendors (I'm working on a spreadsheet to confirm each part and where to buy along with part numbers).
About 3 months ago I installed a small water pump and 'radiator' in front of the computer fan to aid further cooling. It works great. At that time, I also cut the aluminum front shield and installed a hinge to open up the right side to allow lubricating the pistons without removing the shield. I wanted to keep the shield intact to see how the cooling worked out.
I just installed an hour meter a few weeks ago, so I can more readily tell how many hours Box #2 (in use) has operated.
Maintenance and service are a breeze, especially after working on several Boxes (friends as well as mine) multiple times.
AlanMcD has had some great input/ideas in conjunction with my quest to keep these guys running smoothly (thank you!).
I really enjoy using the Box and its simplicity.
Mike