The starter vibrator died on a friends R44 Astro and as it was near end of life we just used a good squirt of "damp start" (Ether based) into the air intake! Worked a treat, started within a half turn every time.
Not sure I'd do this on one that had years of life remaining though as it's unknown what a regular dosing of that would do to the cylinders, but every now and then probably isn't an issue.