Win 2K volume slide won’t stay up

When I tried to adjust the the volume slide on the tray it will not stay put. It moves to the bottom of the slide in three to four “hops” depending on how high I set it to start. Pretty annoying. I need to keep pushing up the slide and listening to decreasing volume – prety annoying. Any thoughts?

Other info – Mixer device (you see this app if you double click on the volume) is ESS Maestro – the volume control slide does exactly the same thing here.