I would sugest to open the library, review if everything is ok inside, take all the tapes from drives and hands, put them in the slots, and then try the inventory again.

It means that for current operation destination was filled. For example if tape had to be unloaded to slot and tape was there -> you get this error message. Typical example is when customers put new tapes inside library manually and they fill slots occupied by tapes currently loaded in drive. When such tape is unloaded destination slot already has new tape and error message stating destination component is full would be generated.

Inspect your tape library visually to see if the slot that NetWorker
needs actually has a tape (or not) in it. If the slot is indeed vacant
(which it should be), then shut down NetWorker again, then remove all
the files from /nsr/tmp except the sec directory.

Restart NetWorker, then "nsrjb -HEv" and that should resolve the issue. If there is a tape in the slot in question, then remove that tape before you do this stuff, then use
"nsrjb -d" to place that tape in a slot that really is vacant.