Really old model 29

Hello, I had seen an older thread about a 29 not feeding properly.
I too have a problem with my 29 .22 pump. going by the different versions of 29's I have one of the first ones being built with the octagon barrel.
Anyways, it will cycle just fine with one shell in the tube. If you stick more than one in the mag tube, they just pile up inside the gun.
On the other, older thread, it was talked about a ball bearing that cured his problem. I would like to know what size ball bearing, and where it would go.
Has anybody had any experience with this issue, on a gun of this age?

Thanks in advance,
HD