I agree with browningautorifle.
The op rod spring should be replaced about every 2000 rounds. I have the USGI spec somewhere on what the free OAL should be of a serviceable spring. I'll have to hunt it up.
I have torn down M1's before where the spring came out in 3 pieces, yet the owner was still shooting the rifle and reported no issues.
Remember that the heel of the receiver stops the bolts reward travel. As the spring gets weaker, the receiver takes a bigger hit with each shot.
You can get a newly made, USGI spec spring here. I talked to Clint McKee, the owner of Fulton Armory at Camp Perry, and he tracked down the original contractor and had them make him new springs to the USGI WW2 print. For only $9, every M1 owner should have a few spares. Surely there's a way to get them to Canada.
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There are several of us here that are very knowledgeable on the M1 and can help with repair, tuning, and shooting issues. All you have to do is ask.