I noticed recently that my MMB doesn't behave right, I had a deep click action set at >30% force, with default MMB behavior at <30%. 

OLED screen shows constant 100% force on MMB with lightest touch now.

Also, no less than 60% force on LMB.

I guess this is a wear issue? Any way of fixing this or I should just go straight to part replacement?

I had a look at this guide Cleaning the Zs Middle Mouse Button Switch (swiftpoint.com) and did some cleaning without dismantling the switch. Didn't help. 

Should I try opening it? Is it what provides analog tracking or is it just for clicking?