Okay, let's take this by the numbers,
said by rcroning:A few things to check and do:
-Take the lens off the camera and try the focus ring. If it turns smoothly and easily, then there is some electronic glitch that needs to be addressed.
With the lens off the camera and the gear belt removed, and the switch on the lens set to M, the action seems to be getting less tight and smoother as I 'exercise' the manual focus. Of course, this may be purely subjective but I don't think so. But it's still not as easily twisted as the focus ring on the Tokina 12-24. (Of course, that's got a physical clutch rather than a switch to disengage autofocus.) But what did you mean about some "electronic glitch"?
-If it is still stiff and this is an older lens, the lubricant may have dried out. In this case it needs to be sent in for a cleaning and re-lube.
Well, I'm sort of betwixt and between on that one; maybe this week I'll take it up to Ace Photo and see if they've got a resident tech on hand.
-When on camera, does the AF work smoothly?
Yes, as far as I can tell, there's no obvious tightness or roughness when using the autofocus.
-Is it possible that the strap is on too tight and is distorting the focus ring and causing the issue?
No. If anything, I'd say the gear strap is a bit more stretchy than I'd like. It's also very smooth on the inside and, if anything, tends to slip on the rubber focus ring embedded in the lens casing. The ribbed focus ring grip on the Nikon is also much less pronounced than that on the Tokina.
-Maybe the M/A - M switch is not functioning on the lens. There should be a S/C/M switch on the camera body that also does this for you. Try turning that to M as well.
Not QUITE sure what you're referring to here. Both the D70 and the D7000 have a little rotary switch on the camera body directly behind the lens mount, but that's only marked as "AF" or "M". However, on the D7000 directly under the mode selector dial on the upper left of the camera body, there's a second control dial that's marked with "S", "CL", "CH" and four other symbols, which I guess I really should look up.