#1
I recently got a Schecter Solo 6 Custom. I like it a lot, except, there is an issue with the tone knob. It has a pair of seymour duncans with the ability to coil tap. Regardless of whether or not I pull the tone knob up, the turn resistance (if that makes sense) is almost non existent.

A brief bump (that I may not notice) will set the tone all the way to zero. In some cases, even gravity will cause it to turn. I checked all the screws and everything is tight. I even popped off the back panel and popped it out to see if I could figure out the problem, but I didn't see anything.

I didn't really know how to explain the issue, so if you want more information I will do my best.
#2
I've gotten a hold of some push/pull pots that are pretty loose like that. Not much to be done short of replacing the pot with something better. Personally, I don't like the push/pull setup. I like standard pots and then I add mini-toggles for splitting.
#3
There is some tips from my side..
A scratchy sounding pot could be a sign that dirt or corrosion is effecting the contacts inside of the pots casing.
Pot" stands for potentiometer. Volume and Tone pots are the same component but a capacitor is soldered to the ground lug of the tone pot. This cap prevents a certain amount of treble from grounding out.
Determine what kind of guitar knobs are on your guitar. A knob for a solid shaft pot will have a small hole in the side where a screw is sometimes used. A press fit guitar knob (common on Stratocaster-type guitars) won't have a small hole or a screw in the side. Spin your guitar knobs around and look for the small opening.