Unlike other printers, The Micro 3D Printer operates at very different temperatures for ABS filament and PLA filament. For ABS, it operates at approximately 265C. For PLA, it operates at approximately 210C. This means if you have just printed with ABS, and you want to switch/load PLA, you will need to rid the nozzle of ABS filament first.
To do this, allow the temperature to rise to 265C while extruding PLA. Click the Heat to ABS Temp button to purge/test extrusion of ABS filament. This will remove/purge all ABS material from the nozzle. The temperature must then be lowered to 210C to print with the PLA filament.
On the other hand, if you were using PLA and now want to switch/load ABS, no special steps must be taken. The temperature used to print ABS is too hot for PLA to handle, so any PLA filament remaining in the nozzle will be removed/purged very easily. Click the Heat to PLA Temp button to purge/test extrusion of PLA filament. Also, click the Fan On button when working with PLA filament to make sure your extruder does not overheat.