"Failed hydraulic tailgate struts are common; the parts aren’t prohibitively expensive, but replacement is not worth what the dealership will probably charge to replace them. Even if you’re not terribly handy, you can probably change them on your own in less than half an hour."
Mazda has issued a recall for its popular 3 hatch, 6 wagon, CX-3 and CX-5 SUVs over concerns the tailgate struts could break.
With pin removed, the larger tailgate strut cannot be inserted into a length of pipe, as with the window strut. This is due to its U-shaped end which stradles and traps the hinge (probably for safety). This requires a slightly different approach: