While your frog is in the bath, you can gently touch the area just above the vent and push up/forward (GENTLY!). The frog will probably try to resist moving forward, and the muscle movements are very similar to those they use when going to the bathroom. A lot of times this will get them started. I've had this work with Trevor multiple times when I give her a preventative bath (she has a serious tendency to get impacted, so I give her unmedicated warm soaks about once a week if I feel lumps to keep things from reaching a crisis point). Don't know how much it'll help with more severe impaction, but it won't hurt anything.