battery problems with my MH20GT

I just got a Nitecore MH20GT and it works for with CR123 batteries but will not work with my 18650 cells. I think the problem is with my 18650's, they are all Zebralight protected 18650s but I think they are on the short side with a small button top compared to most cells. I've got about 20 of those batteries that I use with my Zebralights and would like to be able to use the same batteries with my MH20GT. Has anyone ever tried adding some solder battery contact to lengthen it some or come up with any other mods to be able to use the shorter cells?

If the problem is indeed a length issue I think you could just purchase an appropriate sized neodymium magnet and attach it to your battery to lengthen it for use in your nitecore. I have never done this and I have no idea if the magnet will have to much internal resistance but it seems like it may work.