Sounds like the pushrod runs are not straight enough. More or less straight is not good enough as every bend creates friction. If rotating the inner pushrod frees things up it then you've probably found the spot where the natural curve of the inner rod is more closely matching the curve of the outer rod and reducing the friction.

The real answer is to make your pushrod runs straight, arrow straight. This does two things. It reduces friction and it eliminates slop in the connection.

As a last resort, if you absolutely can not straighten the pushrod run, you can switch to a metal pushrod. But it must be a good fit in the outer sleeve or you'll have even more slop in the surface. So you need to cut short sections (1/4" or so) of the inner pushrod and slide them onto the wire pushrod every few inches and fix them in place with a drop of CA. This will keep the wire from wiggling around in the outer tube. If the pushrod still feels stiff, try to bend the wire to match the bend in the outer rod to reduce the friction even more.

Dave