Hi Amy! I got your email looking for stirrups for your cart. You can get stirrups to fit your cart from Heindle Engineering...couple of guys that used to work for the folks that made your cart. Dave and John do really good work, honest and reliable on shipping. Here is their website. They make an AWESOME jog cart...most comfortable cart I've ever driven...ever.
They can supply all kinds of parts that work on a variety of carts by the way.