Swede M38 Bolt Issues

I've got an M38 Swedish Mauser, that I've got an issues with. I've had it for years, and finally decided to see if it can be repaired. If you can picture this, when the bold is completely open (?), in other words, all the way to the rear, it rear of the bolt sags so much, that closing the bold, it can actually ride up on top of the next round in the magazine. If the bolt is held up as it is closed everything works fine. And it shoots great.
I don't know what the diameter of the bolt head should be, or the inner diameter of the rear ring. Are there larger bolt sizes? Any thoughts?
Thanks!
Brian