To avoid having issues with putting blades on your clipper and not getting them locked on, you may be doing it improperly.
Every groomer does not read the clipper manual, usually somebody in the shop or in a grooming school shows them how to operate the equipment, this is bad.
Here is a link to a video we made and put on our company Facebook page. Follow the link and watch it, its good information and it could save a call to your sharpener when your having an issue. Here is the link:

https://www.facebook.com/northerntailsinc/videos/196153891449620/?v=196153891449620