At the recommendation of a LEAF forum, I purchased this set of these two mini toilet plungers. Just remove the shaft and the rubber plunger fits perfectly over the entire shock tower collar. Because it slips over the lip of the collar, there’s minimal chance of water entering the shock tower: Mintcraft Plunger (1, 2-Pack) https://www.amazon.com/dp/B07YBDY1WT/ref=cm_sw_r_cp_api_i_AMJ7C8V3K3VR5SRQMKQP?_encoding=UTF8&psc=1
Here ya go, perfect fit: https://www.amazon.com/dp/B07YBDY1WT