doing some lapping and had trouble getting into 2nd.
any ideas of what is causing this?

 

Were you turning while shifting? It sometimes happens to me while tracking and turning which puts a lateral load on the system. Best to shift with finesse while doing a two part shift, into neutral then into the next gear. Usually happens to me from 2nd to 3rd. I avoid shifting while turning. Is it possible you didn't have the clutch fully depressed? Also could possibly be your transmission mount is going out, a known problem.