If you're losing gap it's cause you need to readjust the rollers so that the adjustable roller is coming up from underneath the drive roller when you set the gap, otherwise it will move when milling. It's very confusing but I finally got it sorted out when I got my first MM mill years back. Here's the response from Fred that explains it. If it's still not making sense I've linked the thread which will help to understand it more - most info is on page 2. Btw, don't overtighten the adjustment screws or you could strip the base.
"All the hex head bolts allow you to do is overtighten the bolt, and ruin the threads in the frame. If you make sure that the adjustable roller is coming up from UNDERNEATH the drive roller on both ends when you set the gap, then the thumbscrews should hold. There is TWO positions of the adjustable roller where you can set the same gap, one with the roller coming down from above, and one with it coming up from underneath. If you notice the thumbscrews are OFFSET from the centerline of the knob. they are below the knob centerline. If you imagine the grain pressing against the knob trying to turn it while you are milling, you can see that the thumbscrew will either get pressed against or pulled away from the knob when milling depending on how you set the gap. We have found that the gap should hold with the thumbscrews are finger tight if the gap is set such that the roller is coming up from underneath the drive roller when setting the gap. To state it another way, the gap should get smaller when you turn the knob on the drive shaft side of the mill clockwise."
https://www.homebrewtalk.com/forum/threads/adjusting-monster-mill-2-0.375038/
Rev.