Basically this change greatly reduces the effective value of the bandspread capacitor. This can be done by removing rotor plates from the bandspread capacitor but a simpler change is to put a low value capacitor in series with each section of the bandspread capacitor.
You'll need three 10 pf capacitors.
**** Warning Warning ****
When cutting the three connections between the main tuning and bandspread capacitors there is a chance something will go wrong. You may be able to fix it by running an interconnect jumper across the top (insead of capacitors) or you may have a boat anchor in the nautical sense...sorry.