Note: I'm in the USA and we call globes "bulbs", so I'll try to use the Aussie syntax but I might slip now & then in the following post.......
I met up with some robotics buddies of mine today and we talked about this very thing. The subject came up because within the couple hours we were hobbying around and mixing games of pinball here & there, three #47 globes had to be replaced. This is in a game I just completed shopping out, part of which was installing new ones throughout the entire game, and I've already replaced ten or so within the past week. This crap just has to go. On a side note, I did start re-installing some of the globes with GE bulbs that were originally in the game and they are more reliable, but you just can't get good quality globes anymore.
Anyways, they both told me they bought some bright white LEDs somewhere off the net at 1000 for $10 (US). I'm going to find that source and get some to experiment with.
A couple thoughts:
1) Seems like maybe installing the right value of capacitor might blend the applied voltage to help make the LED light similar to an incandescent filament? I've seen plenty of devices that have a lingering LED glow until a capacitor is done discharging. Of course you don't want it to linger for seconds like that, but the proper capacitor value might work like a champ.
2) At that price, ganging two or three together to replace one bulb may help in terms of dispersing light in a less directional manner?
3) I wonder if it would be as simple as taking an LED to the bead blaster for a couple seconds to create a home-brew diffused LED for next to nothing? Hell, even a few seconds with some sandpaper would achieve a similar finish on an LED.
As I mentioned, I'm going to experiment with this, probably with the help of my robotics/electronics guru buddies, and see if something can be made to work just right. I have plenty on my plate that I'm behind on right now so it will be a while, but I'd certainly like to wean myself completely off those crap globes. The thought of not replacing them for several years would be music for the soul.
If I can make something work right, I'll just bust the glass off the huge bag of expired #47s I've got and solder the LEDs into that to make for easy installation. After a dozen or so, I'd guess the process would go pretty quick and you'd have enough to outfit a game in a half-hour or so. Probably have to make two or three different configurations to replace globes in different types of places, but if it will save burned out globe frustration, that's worth a lot to me.