Capt,

My guess. The left turn is not related to the dash problem. It is probably a bad lamp.

The dash lights may go through a dimmer (rheostat) on the headlight switch. It's either dirty/cruddy or broken in two.

It looks like there is a fuse in your fuse box that says 'panel lights'. Is this the dash lights. Do you get voltage on both sides of the fuse? This is probably before the dimmer so It only proves there is power going to the headlight switch.

Stuart