replace them with vintage ones that have locking screw and not snap-in. do your research to find matching ones. there are also wood knobs for sale often offered here, but very pricey. they claim to improve performance which i doubt, but definitely imrpove looks of equipment.
The other way is to use nail polish with one thin layer over the knob pins (if the pins are not plastic). Once you snap your knob on, to remove you may use some screwdriver as lever that will be able to crack the polish and release your knob. Also within the time it may go off by itself and that's when you can repeat with another layer.
The other way is to use nail polish with one thin layer over the knob pins (if the pins are not plastic). Once you snap your knob on, to remove you may use some screwdriver as lever that will be able to crack the polish and release your knob. Also within the time it may go off by itself and that's when you can repeat with another layer.