Jon,
I bought my M37 28 ga. directly from Ithaca in 2009-10. It had a similar issue as yours. I sent it back and at the time I sent it back, one man specialized in servicing the 28 ga. He was out on medical leave with knee surgery for several weeks. When he got back, the issue was remedied. "Timing" was the issue, whatever that means and how it was adjusted. It has performed flawlessly since which means I have just planted the kiss of death on it at 830 pm EST, March 2, 2023. Now why did I just do that... Gil
