Are you sure you have Andis A5 or did you mean Oster A5 Clipper, if this clipper is A5 Clipper, You need to check the Lever for wear, The front of the Lever show wear on both side, Like white color and is not squad this Lever is worn. Need to replace. This Lever moves the blade side to side fully. if the Lever is worn the blade will not move fully side to side and the cutter blade the smaller blade will stay in the middle with hardly no travel to side to side and will not cut the hair even if you purchase new blades. Also I would like to mention if the Oster Locking Hinge is worn out and don't have the require tension to hold the blade in place the blade will not cut. How do you test the Oster Hinge on a Oster A5 Clipper,
(1) first close the hinge, in close potion with your finger nail try to open the Hinge, if the hinge slightly open or opens loose the Hinge is worn. if the Hinge is good it will not open or move and your nail may just brake your nail.
Many of my customers run into this type of problem, and the problem can be solve easily by checking these parts first.
One more item I would mention here if replace the A5 Hinge make sure you get the A5 Hinge not the Oster 76 Hinge they are driferrent, The A5 Hinge has on the back two wire's sticking out that fit on the Oster Latch for the A5 Hinge, the Oster 76 Hinge would not have these wire's on the back. I recommend replacing the Latch when you replace the Hinge. I hope this helps any body that have a A5 Oster clipper or A Oster 76 Clipper.
I have over 20 years in the repair business of Sharpening & Clipper repair. Mannys Sharpening 323 263-4697