Mentoring Guitar - Need Help - SOLVED :)

I don't normally play except to test my builds but with the recent purchase of some new packs I thought I'd take the time to level up my Tester Sim in some skills he doesn't have. I've been concentrating on his musical skills and thought I'd do the relevant aspiration while I'm at it. All he has left is to mentor someone for 3 hours but no-one in this game picks up a guitar so I can mentor them. I spent all day at the Arts Centre only to have one Sim pick up a guitar and put it down before my Sim could stop what he was doing and walk across the room. It's getting very frustrating as I want to get on with the Jungle Adventure aspiration.

Anyone have any ideas how I can finish this please? It seems to me we need a menu command on the musical instruments that says "mentor .." and a pop up box comes up with a list of those on the lot much like "play cards with .." etc.