Shimano derailler issue

[kayd]

Sorry about the hiatus - I've been out of town. Here are a couple pics of my old front derailler and thumb controls. Again, the front controls will get the derailler to the larger two chainrings, but it springs back to the smaller ring as soon as I let go of the trigger. Any suggestions of how to get this to work again? Thanks. Kay[attachment=3411][attachment=3412]