Since we're talking speedo bulbs - I can see my speedo just fine, but the odometer is pretty dark. I haven't even looked at this myself, so apologies for that; but is there a separate bulb for the odometer?
There is a difuser in the speedo that can be carefully pulled out. Pull the speedo bulb out and if you look in the hols there is a white difuser in there. You can grab it with a pair of needlenose pliers and gently wiggle it back and forth until it comes free and then pull it out(don't let go of it). It allows more light to shine inside the speedo.