Strangest issue with Vertex UF20

[mseepman]

OK, so as typical for me I like having an abundance of equipment on hand for whenever I need it. As such I bought a brand new UF20 back when they were the newest and greatest media reactor with a plan to do biopellets. I never ended up doing them and its been boxed for about 2yrs.
A little while back I ran out of prodibio and then by chance I went on vacation and upon my return I'm noticing my phosphates are too high. Thus I decided to open up the vertex and put in inline with gfo. This is how i've discovered the issue.
After removing the cap on the UF20 I can not get it back on. I have tried everything....it just doesn't fit! I don't know how this is possible but something is wrong and it won't thread back on. Its so far off that it doesn't even seem to be from the right piece of equipment. Has anyone else experienced this? Its never been wet, I was just examining it to determine how to plumb it in. This feels like a retarded issue but i've done everything I can think of to put it back together.