I am a big fan or the ARB Jack as it is firstly a simple easy to use piece of equipment that can lift my vehicle with ease, and while it has some design flaws, and the endless opportunity to pinch my fingers in use, it is will what I prefer over a Hi-lift, mainly around my own safely preferences.
If you follow anything I do, you know I 3D print a replacement lowering lever to have as a spare or to outright replace the white metal lever that breaks. I did this as when I receive my jack brand new in the box, that lever was snapped at its base, making the jack not very usable for me, and the 8–12-week lead time to replace it was a “are you kidding me?” moment. I went to my favorite cad program and created a replacement design that works well in PLA/PETG/PC and ABS. (PLA seems to have the correct properties for hardness to push the detent ball and stay rigid enough to repeatedly depress the lever.

Recently, I had an Instagram follower, let’s call him BigMoney (Not the real name on IG), reach out after purchasing my lowering lever and pointed out that the quick release lever to raise and lower the jack hook (called that in the manual) on his jack had cracked. I went and looked at my jack and there it was a crack at the pivot point to the quick release lever arm. BigMoney asked if I could create a replacement, but this was super close to bicycle parts and I looked high and low for a M6 Quick release lever, but all I could find was M5 threaded units. So, I settled on the M5, and for a few dollars on Amazon, I had a replacement. No, at no point am I telling you to do this as an under-spec part will kill you if it fails in use with this jack but seeing the slotted design of the hook into the jack body, and that the clamp is only used to prevent random movement of the hook/clamp, I assumed the risk of this part change. You do so at your own risk, and I am not telling you to do what I did.

I do wish that ARB would come out with a kit to retrofit these parts to items more substantial, if you know anyone there, please pass this on.

Quick release seat post, needed for the pivot and lever.
https://www.amazon.com/gp/product/B09ZV4SCCN/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

M5x60mm Bolt
https://www.amazon.com/Socket-Screws-Metric-Machine-Threaded/dp/B0969W38T6/