What should I do about the floor switch?
First thing first- - - -
CHECK
THE
VOLTAGE
AT
THE
HEADLIGHTS!
Everybody wants the quick fix. Back in the dark ages, Sun electric Co. had a slogan on all their machinery: "We test, not guess!" If there's a noticeable voltage drop that you can definitely attribute to the dimmer switch by checking the voltage before and after the switch, replace it. Don't waste time trying to clean it up. Ditto for the headlight switch at the dash.
You can avoid a lot of problems with headlights the same way it was done 70 years ago- - - -install relays that provide full battery voltage to the lights, and use the headlight switch and dimmer switch to control the relays. Heavy wires are run from a good source of voltage such as the battery cable at the starter to a junction block near the headlights, and relays are installed to direct that voltage to nothing but the lights at the proper time. No series of connections through the headlight and dimmer switches, and no small-gauge wires to rob voltage along the way. It worked on 6V systems in the 1940's, and it will work just as well today.
Don't forget to run a heavy ground wire from both headlight connectors to a clean, low-resistance point on the body or frame.
Or, you can pay some highway robber an outrageous sum of money for "bright" headlights which, BTW, use the same system of relay controls I just described. "Ya pays yer money and ya takes yer choice!"
Jerry