I tried to plug it in my D2, however the crane plug won't fit. I've tried forcing it, however I still cannot get it to do in. I inspected the crane plug and it appears to be in good condition. I've tried looking on the internet, however I cant find anyone who has had a similar issue with the D2. I know that Steiner units are infamous for their prolapsed switch plugs, however I haven't read anything about the plug not being able to fit.

I just had this issue with a D2 and ModButton Lite. No matter what I did, I couldn't get the plug to seat. Contacted Modlite, they said it's a common problem because the D2s often have a very tight plug receptacle. After some back and forth, they offered to take the button back to look at it. I asked that they replace it with one on the skinnier side of their spec. A few weeks later, a new one arrived. I just installed it a few hours ago. It was still a little tight but nothing like the first one. Coated it lightly in dialectric grease, worked it back and forth, and it snapped right in.

Not sure that helps, but it definitely is a known issue that the D2s are tight.