Front turn signals not working

I cannot speak to your model car, but these are "generally" some of the problems in my 67, not necessarily just for dash lamps

1.....Harness connector pins were either loose or broken on the PC board. There's a thread on this board that is very good for repair

Printed circuit pins repair

2....May not apply to your model, on mine the gauge limiter contacts were not making contact with the board traces. In the thread posted just above that is addressed

3...Because the board is copper it corrodes and oxidizes. This leaves lots of problems for the dash lamps, clean the copper, replace the lamp sockets, or clean the socket contacts and bend the contacts so then make more firm contact

There is NO reason you cannot lay the cluster down, look CAREFULLY at the traces, and figure out "where stuff connects." For example, all "illumination" dash lamps are grounded on one contact, and paralleled together, but in cars with TWO circuit boards there is a jumper connector in the harness that connects that "split" circuit together on the two boards. This is a clue. If one half is working, the other not, it's likely one of those two interconnect pins on the two boards.

4...Gauge stud nuts were loose corroded, gauges were not making contact. Loosen / tighten the nuts or replace them

5....IVR was bad. (If you have a Rally dash, the IVR is built into the fuel gauge)