Anerosing highs and lows

First couple times I used my progasm I could feel my body shaking and then about a week later I did not have the shakes but I could feel the energy in my spine several times but it never moved. Fast forward another week till today and there are times I get those shakes and times I don't I feel like a couple sessions were duds. I know I'm still at a noob status only doing it for a couple weeks but sometimes I feel like I lost the new ness of the ride. Maybe I have my expectations too high? Maybe I should get another model? Maybe I should try it for a couple more weeks? I have been doing the do nothing approach so far. I'm not new to anal play but I am new to the Aneros. I have tried different positions maybe I should change positions and see if that works