We had the same problem, actually found your post as I was searching for an answer. Don't know if you've found your solution yet or not, however, I'm sure there will be more with the issue and I'd like to let you/others know what I did.
Problem - Grinding/moaning from autosampler (Dionex / Thermo Fisher AS-DV) sound when needle would inject into polyvial. Eventually resulted in "interrupted" status for samples which ultimately rendered the analysis useless.
Early-Symptom = Our IPC (internal performance check) was deviating from it's usual behavior. EPA 300 for anions allows us +/- 10% for the 5 anions. Would normally be around +2% or +3%, all of the sudden (right around the time of the grinding) our IPC would be around -7% or -8%, telling me that there was less sample getting into the system.
Symptom at time of repair = removed the sample out line from the HPIC (Integrion) where it goes into the actual system. Noticed that my sample was coming in at a very very slow drip.
Solution - Took apart the sampler system, so take off the front cover, the protective cover around the plunger, and the top cover using the allen wrenches specified in the destruction manual, and a small Phillips head screw driver.
Next, removed the "screw" that is holding the plunger and sample out line in place. Slide the sample out tubing out, GENTLY, then wiggle the plunger out, trying a few different angles, the tip is oriented to get a 1/4 wrench around it, but it does have flat and rounded edges. Once that's out we took out the base, where the plunger normally goes into, which you just wiggled the plunger out of. Removed the sampler tray, knob in the center.
Next once the sample line was free we took it down to an HPLC and ran water through the line in the reverse direction. This showed us a slow drip that even at 4 mL/min wasn't a stream that you'd expect. So we used a syringe for a GC and cleaned out the orifice of the plunger a little. Trying to dislodge whatever was causing the issue. This may have widened the orifice a little, but really it won't and has not made a difference.
Lastly, we hooked it back up to the HPLC and set it to 4 mL/min again, alas we had a stream. Brought it back to the IC, hooked it up, held my breathe and pressed "start" in chromeleon. It worked, no grinding, no moaning, just smooth sailing. Remember to run a bunch of rinses as your hands and whatever you use to clean the plunger out with will have various compounds and elements on them. If you don't have an HPLC to do this with, you can simply use a syringe that can hold water. Use it to backflush the plunger, attaching to the same spot that would go into the HPLC.
I know this maybe a little confusing, but in conjunction with the instruction manual, this isn't too bad of a fix. Future note, will be buying 2 more assemblies to have on hand just in case this isn't as easy next time.
Hope this helps.