Dash lights

If your WS has where the bulb goes in the plastic "socket", then that twists in... those get frequently loose.
If that's how yours are, then you need to bend the 2 little brass contacts "upward" on the socket so that they have much more contact tension on the dash contact area.
It makes a world of difference with a little more tension.

 

If it's what I'm thinking you are talking about these bulbs that you insert into the socket and twist them in to lock them.



If it's that bulb take a screwdriver or pocket knife and pull them little wire contacts out some.
If them black sockets are in poor shape you might have to replace them.

Am I close or is it another setup?

 

Condo,
Great pics. The non wired ones are typically used with a printed circuit board on the dash backing.
Some of these rely on just the 2 brass tabs to hold tension, even tho they also have the plastic tabs that retain them.
The ones on your right side pics have the metal interlocking/retaining tabs. If those get loose the tabs need to be bent down (away from bulb).

The ones I first was talking about are pictured below.
In he has these, then the tabs have to be bent slightly the same way, but in this case to put more contact tension against the printed circuit board/mounting hole contact surface.
The style below makes contact on the outside surface of the dash panel/printed circuit board, while the ones you pictured make contact on the inside of the dash panel/printed circuit board.

Bottom line, the OP first needs to determine which type he uses.

 

I don't think the Western Star has an instrument panel of sorts but consist of individual gauges and I'm thinking the left picture with wired sockets. Then again I haven't been in one in awhile. But yeah that type bend the wings up. That's your typical circuit board socket.

Either one the contacts on the bulb need pulled out too. Sometimes they get knocked off to the side or sitting in a worn socket they might not make good contact.

I went to change a bulb yesterday for a friend and his circuit board was burnt in two. I told him to buy another one. I didn't feel like jury rigging.

 

True, it slipped my mind about the individualized setup in Western Star. I'd also agree and tend to believe he has the wired sockets.
True about the bulb contact itself (bulb "loop" wires). They are often a problem child for good contact. Sometimes misaligned or socket contact gap too wide/open.
I usually find the inner tangs tend to "relax" with time and have too big a gap most times. I usually take two pointed knife tips and snug them up a bit, for a tighter grip on the bulb base & bulb wires.