I’ve got that problem now also. Understand it’s just another’s ugly symptom of PD

I use Werther's Original hard candy, having the candy in my mouth reminds me to keep swallowing.

If you like there a exercise program for face expression and drooling is one of them there seven steps if u need the link let me know

https://www.youtube.com/watch?v=9H3WExYf_70 if u cant open this for drooling exercise just put in Parkinision drooling exercise in search

Drooling in PD is related to deglution swallowing is less so we accumulate saliva with drooling as a sequel.Chewing gum .,drinking water move yours mouth so accumulation of saliva is less as well as drooling try it may work