Both blades on Troy built hedge trimmer move at the same time

SOURCE: Black and Decker 16 in Hedge Trimmer

I use a dremel with a sharpening stone, if u don't have one you can also use a power drill with a small sanding disk (1 inch) and course sand paper (30 or 40 grit). or you can use a bastard file. its too tight to use any kind of angle guide so just take your time and do it by eye. it shouldn't take much to get them sharp enough to do the job, over-sharpening is unnecessary and dangerous, and will make the blades dull faster. sharpen all the free blades, top and bottom, then start the trimmers to advance the blades to free up the sides you couldn't get. i use a light penetrating oil to clean the blades first, then lithium grease spray to lubricate.

SOURCE: Electric Hedge trimmer will not cut

more than likely it damaged the inner gears or drive pins that make the blades reciprocate and need replaced. if you would like instructions to repair it yourself i will send you them or you can take it to a service center.

SOURCE: Ryobi 18V Hedge Trimmer Blade Question

Just buy a file and push 3 or 4 down strokes down the same slope of the cutter toward the sharp edge. Never file on the flat top of the cutter, only on the slope. Support the frame using a saw horse or pick-up bed. The support makes the file cut the metal better. You can do the same thing with chain saws. You just need the file that fits the cutter. You just hold a consistant angle and count out the same number of strokes. Also, clean out junk between the moving parts, tighten any loose screws, and drop a few drops of 3 in 1 oil between the moving parts. Having things sharpened at a shop is inconvenient and expensive.

SOURCE: My B & D electric hedge trimmer blades are frozen

spray liberally with wd40, let side and hour spray rag with wd40 and clean blades and look for any bent teeth in blade that maybe binding them as u clean use pliers and screwdriver to move if any found, it is likely that wither sap dried or rust formed and is creating too much friction for blades to move wd40 will help free up blades

SOURCE: My Black and Decker hedge trimmer's blades won't

Your blades are stuck together.
Had the same problem: when I turn on the trimmer, the motor would hum but the blades won't move.
What I did:
1. Sprayed a ton of wd40 between the blades
2. Took a screwdriver and kinda wedged it between the blades to get them unstuck. Also removed some guck between the blades.
And it worked!