How test/inspect 2.0L DJet throttle body before swapping it in? Options

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Hi - the '75 DJet car has a stumble that happens at a couple points in the rev range and at certain RPMs when the throttle is held constant. It rarely happens when the throttle is being exercised up/down the RPM range (like accelerating through turns etc).

I'm thinking worn throttle body "fingers" or the trace pad they travel against (yeah, wrong terms I know) but I believe this could also (maybe) be a sticky advance weight in the distributor.

Any why to test the spare throttle body so I don't swap out the wrong thing?

OR

Should I just pull and open the plastic cover on the one I have to see what is up? Doesn't look that hard to remove it.

What say you gentlemen, and please do liberally apply terminology dope slaps.

Thanks!

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Thanks for the respsones.

Found this earlier which is what I'm wondering about;

Track Wear: Over time, the wiper track for the accelerator function will wear. Wear will be especially high at moderate to light throttle angles, corresponding to part-load cruising. Click here for a link to a 60X photo of accelerator track wear. While this TPS track is still good, the re-deposition of gold worn from the contact fingers by the wiper can be seen, and eventually will become sufficient to bridge the traces. This wear causes arcing and poor contact, resulting in the car "bucking" at a constant throttle angle. "Bucking" is a fairly common complaint and is almost always due to track wear. Check by disconnecting the harness plug to the throttle switch and driving at a constant throttle angle under part-load. If the bucking is gone, it's due to the switch. As I mentioned earlier, if you go to http://www.914world.com/ and search for user "davesprinkle", he's made a kit to replace the worn circuit board that restores your TPS to like-new condition.

https://members.rennlist.com/pbanders/DJetParts.htm