[PbFut]

The fact you are getting some light and some odd function of the turn signals points to poor ground or connection of power to the cluster. The ground is really a bugger on the cluster. The attaching nuts for the circuit board (plastic film) are the ground points for negative side of the lamp sockets that you rotate into the cluster. The contact of the circuit board to the grounding nuts of the cluster is often compromised when moving things around in that area. I had this problem when I added a Tach. I found the problem by accident after messing with the front turn signal circuit half the day. Adding a jumper lead, looping to both circuit board mounting post, and then to a good ground on the dash fixed all the problems.
This picture is non Tach circuit board as viewed from the front of the cluster. The four lamp sockets across center of the board are the illumination lamps. All the others are indicator lights. (Turn, Brake, Hi Beam and I can't recall the last one).
The two 1/4" holes on the upper left and right are the grounding points. You can also see that one of the grounds only grounds one bulb(Right side) and also runs into the harness connector. The other ground point is common for 3 of the 4 illumination bulbs, the bright light indicator, and the 2 turn signal indicators. Because of the common grounding of these indicator lights, it is why some seemingly unrelated items act strangely when one of the cluster grounds goes bad.