I use an ultrasoninc jewelery cleaner from Harbor Freight.
Tip: Fill the ultrasonic cleaner with water, then use motor spray or other solvent in an empty paint jar, baby food jar or whatever. The sonic waves travel through the water, through the glass and into the more expensive solvent. Just be sure to use a lid on the parts jar or keep the water level below the rim of the jar. Really cuts down on clean up too.
HF has a local store here in Minneapolis, so it was easy to acquire.