Remove the chambers and pistons and remove the damper plungers.
Clean everything really well and turn each assembly upside down. Fit the pistons into their chambers and give them a hearty spin as you release them to fall. Repeat this several times. There should be no sticking or hesitation. If you encounter same, switch pistons as it is possible that the PO swapped them and didn't tell anyone.
If you find that there is some level of hesitation work the piston up and down over the period of hesitation without spinning it until you produce a shiny spot on the inside of the bell. You aren't supposed to do this, but IMHO it is acceptable to smooth that spot LIGHTLY with some 2000 grit paper. Some folks will say that this is a no-no and I agree to a certain extent, but the reality is that these carbs or OLD and there are going to be OTHER minor glitches that are similar but don't keep the engine from running decently. Wash the piston and bell down in hot soapy water and dry them before continuing by repeating the process.
BTW: There should be a very small protrusion on the face of each piston that stands a couple of thou proud. Depending on the carb model they can be of brass or plastic. This is there to keep the piston face from COMPLETELY shutting off the air flow over the bridge.
Once the pistons move well, remove the needles and install the pairs back onto the carb bodies.
Now see what you have in the way of "drop". If you still have some hesitation, try changing the torque on the bell securing screws.
The piston will probably drop smoothly now and land smartly against the bridge.
Now roll each needle across a bit of glass to see if one is bent. If one is, you obliviously should replace it with one with the correct station profile.
Once you are satisfied that the needles themselves are okay, install them on to the pistons and repeat the drop tests.
If hesitation remains, drop the jet by about a quarter inch and retest. This will get the jet low enough to rule it in or rule it out.
Raise the jet to exactly flush with the bridge and then adjust it down to about 0.065". The butt end of a vernier caliper is ideal for this. This will be a good starting point for your mix adjustment, assuming that the float levels are identical and to spec. If they aren't make them so.
Finally, take the bells back off and install identical damper springs. If necessary, and it is often advisable, replace them with new ones.
Use an oil squirt can to fill the wells of the pistons to their tops and install the bells over them again.
Last step is to install the damper plungers. Push them down slowly to avoid splash back of the oil.
The rest has to do with precise linkage adjustments, checking for vacuum leaks, possible throttle shaft and bushing wear, etc.
Jack