3 way circuit with single pole switch???

[Ron Van]

BTW I think a 3-way switch is SPDT

You are correct!

I agree with your circuit except I don’t think the 3 lamps would be in series they should be shown as parallel.

Absolutely!

 

[MRubenzahl]

Any DIY suggestions for how to correct this or should I call a pro? I'm fairly handy (added extra outlets, changed single to double gang, etc.) but I'm scratching my about how to locate the "third wire" (traveler?)...

Not sure if anyone suggested this. You could go with wireless controls, e.g. Lutron Caseta. Replace the switch with a Caseta and use a Caseta Pico remote at the second location. Nice thing about the Caseta is that the remote looks exactly like the switch and mounts to the wall but is removable. (Bonus: Switch is also controllable via an app and home automation, Alexa, etc. should you so choose.)

Lutron is not cheap ($70, but might be a deal on Black Friday) but a lot less expensive than having an electrician run an extra wire for 3-way switches.

 

[Ron Van]

I’m all in favor of smart switches and plugs but if it were me, I’d want to fix it and then add the smart switch.