Model 39 follower issue

[Quick7]

Hi All,
New member here. I've always been interested in Marlins since inheriting my Granddads 39. It a non prefix model with the serial number being in the four thousands.
Recently while I was reloading the tube, the follower and spring slammed closed. I took it apart to investigate and attempt a fix. It appears that the little notch on the follower and the catch on the tube are not making a good enough connection to hold the spring tension when the outer tube is pulled out to reload. Once I reassemble it and try to load a round into the tube, I can pull the outer tube back about 3/4 and then the spring tension get too much and the follower gets by that retaining notch and slams into the receiver opening again. I'm still learning and I'm not sure if something is broken or if something is just worn out. Hopefully this description makes sense...Any help would be greatly appreciated.
Cheers. Matt