The image below outlines the process for regular sharpening pruning loppers to keep them in good working order.
At the bottom of the page is a short video demonstrating the lopper sharpening process.
Sharpening your Pro-Pruner (refer to diagram below)
Note: If using the TopMan double sided diamond sharpener, use the coarse 300 then the fine 600 side in place of the blue and red above.
Download PDF of Pro-Pruner Technical Notes