One more electrical demon.....

OK!!!! LOL

TS indicators are simple, possibilities:

Indeed cluster ground, if you have not done so add a ground pigtail just for "general principals" from a ground point on the cluster, bolt that to the dash frame or column support

The TS indicators are simply 2 extra wires branching off the L and R wires for the front, come out of your connector, and go right up to the cluster connector

Could be bad pins on the cluster board or connector, weird they would both "go out"

Bulbs and sockets................

I assume you have checked and the front (grille) TS lamps actually do work

High beam indicator......This is a simple wire that branches off the high beam feed coming off the dimmer switch and feeds right up to the cluster. Same as above, bulbs, sockets, connector pins, cluster ground

The cluster illumination lamps and other dash lamps are a bit of a "trick"

There are TWO power sources for the headlight switch, one of them comes off the tail fuse and feeds to "B2" on the switch. ............So your park and tail (and side marker if equipped) MUST work FIRST

Inside the HL switch, power is fed to the lamp dimmer, you twist the knob to the left. WIGGLE the daylights out of it and see if anything happens

So power goes through the dash dimmer and out of the HL switch on TAN. .......that goes down to the small INST fuse in the fuse panel, so that is ONLY HOT when........

The tail fuse and circuit is working

When the light switch is in "park" or "head"

and when the dimmer knob is twisted "some" to the left.

All dimmer controlled lamps go from that fuse out on orange wiring to the various lamps