Scott - I agree with Todd. My guess is this has nothing to do with your
spinners and everything to do with cleanliness and/or debris on your RT shim
tube and maybe (hopefully not) your probe. This is timely as literally
two weeks ago I had to remove our RT shim tube for cleaning and warm up our
CPP as we were experiencing intermittent problems with samples not inserting
properly. When the problem would occur, the sample down sensor was
triggered as if all was well. But under ICONNMR, locking would sometimes
fail and shimming would frequently fail. I eventually began to focus
on sample insertion rather than shimming when I tried to spin. Spinning
was unsuccessful (0 Hz) and furthermore I noticed the sample down sensor trigger
was intermittently lost while trying to spin.
Some suggestions would be:
* Try to spin at 20 Hz. I think a sample rotating but not making it to
20 Hz versus not moving at all is informative.
* Run a gradient profile and compare to a previous known good profile.
* You mentioned seeing a line 1 kHz broad. Your lineshape here should be
informative. To borrow from solid-state NMR, if it looks similar to an
axially symmetric powder pattern this may indicate your sample is in the probe
but sitting too high.
Good luck!
Mike
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Received on Thu Jul 16 2026 - 04:24:35 MST