I’ve had a HF lift for about 10 years, and was frustrated that it only went up to 26 1/2" as it was just short of the lip of my truck. Went out bought some hydraulic fluid as I know some fluid leaked out, so maybe topping off and bleeding the system will get it to go higher. I read from the tread that the normal height was 28.5” maximum lift. Turns out, 28.5” is not the max on my old model.
Adding hydraulic fluid and bleeding the system certainly did not hurt as it pumps up stronger, but did not raise the lift past the original 26 ½”.
I am too cheap, and too lazy to have to buy a new card and modify it, so I took the easy way out, I added 2x8x8 boards to the top of my cart to get it up higher by 1 3/4”.
A 2x8x8 had a height of 1 ¾” after it is made smooth, which I had cut so it was 6” longer than the HF cart bed to add some additionally stability. Tip, have Home Depot cut the wood as doing it by hand is tough as the cheapest wood is green.
I also brought six 2" carriage bolts and nuts, and drilled holes through the wood and the HF cart bed. Use titanium bits to punch through the cart top.
Pay particular note where you drill the holes, as the bolt can interfere with the scissor action down below and the table will not go down.
Whole thing cost less than $10.
When I use the cart I throw a cloth doormat in top of the bed so carriage bolts don't damage bottom of the game. I did countersink the top carriage bolt head so it it not stick up very high.
I also used L brackets to allow my handle to fold down. With the raising of the bed, I had to raise the handle mount on the L bracket so the handle still folds flat.
Hope my solution adds to options, this is a great thread and learned a lot from it, especially on bleeding the cylinder.