Ultrium 215 initialization errors - problem with vertical mounting?

[DarrenReed]

We have a 215 drive mounted in a server vertically (on edge), and we seem to be getting random initialization errors on backup jobs (even after the same tape ran fine on previous jobs earlier that day). I have noticed that the tapes don't seem to always go in smoothly when mounted this way - is there known issues with this mounting style? I looked thru the install document but did not see any warnings about it..