My Honda Harmony II lawn mower won't pull itself but when I raise the back wheels off the ground they turn.?

The mower Model HRR215TDA pulls a foot or so and then stops pulling. When I lift the handle to get the wheels off the ground they start spinning (like they should) but when I put them back on the ground they just can't turn to pull the mower forward. I tried raising the wheels to the highest setting/tallest cutting height but no improvement. Also, I took the control that adjusts the forward speed apart and the cable didn't move freely so I sprayed some oil into the cable-there was some rust on the cable. It is set to the fastest speed. I just don't know why the wheels won't pull the mower and in 95 degree heat this jut isn't working for me. LOL