Step 1 – Check whether the mowing height adjusting knob is locked, meaning it doesn’t rotate freely when not pushed down. Also check by pushing it down and feeling resistance whether there is a spring in it.
If Yes – Proceed to Step 2.
If No – Remove the mower cover, pull the knob out, insert a spring and close. Put the mower cover back on and lock it well. Try changing height of cut and make sure when you do not push the knob down, it is locked by the cover and doesn’t rotate freely without being pushed in.
Step 2 – Check whether the mower cover is locked well on both sides.
If Yes – Proceed to Step 3.
If No – Lock the cover well on both sides. Remove the cover and put back in if needed. If it didn’t fix it, proceed to step 3.
Step 3 – If both the above didn’t get to lock the mowing height adjustment knob when it isn’t pushed down, replace the mower cover. It may have been warped. Did it fix the problem?
If Yes – Problem fixed.
If No – Proceed to Step 4.
Step 4 – Is one or both sides of the mowing deck sagging down towards the ground, even though the mowing height adjustment knob is locked well in place when not pushed down?
If Yes – The long pin holding the mowing deck to the mower must have loosened and come out, not securing the deck to its floating mechanism. Get a pin and a new star lock washer and secure the mowing deck back to its place. Take a look at another mower where it is secured, and it is simple and easy to understand and fix.
Step 5 – Make sure the mowing deck is above the chassis frame tabs as shown on the picture below.