Hi, nice to meet you all. I tried to post this earlier, can't find it so if this is a repeat, sorry! I recently bought a Klingenthal-made melodeon, cf, 8/21, gorgeous tone. But it was owned before by person with large hands, mine are half the size, and keep sliding. The bass strap is held by pins/rivets and not alterable. My thumb's starting to majorly protest! Can anyone give a tip as to how to help the problem. I don't want to get really put off but it's starting to be a major issue. Thanks so much.