as stated, you can just silicone them on but the proper way is by pressing them on with new rubber inserts if the old ones are junk. Are the old inserts still inside the sash channel? it's a rubber C shaped piece that goes over the edge of the glass then the sash channel is press fit over it. (remove the rubber seal off the front first then tap it on to the glass over the rubber C channel with a rubber mallet)
Here's a link on ebay but I'm guessing Ames sells them too.
https://www.ebay.com/itm/Quarter-Win...9UIzaC&vxp=mtr