I'm betting the blades are striking the skirt on the back or side. Backing up or going forward, while turning can bend the skirt especially if an object is hit.
Whatever the blades are striking it will be obvious, use a jack stand and get under there and look..
^This :thumbsup:
Are blades actually hitting
underside (the horizontal decking) or are they hitting the side skirting?
Raising it up and looking under (while using safety stands), it will be obvious where it's hitting by where the shiny metal is.
When you say they don't get within 3", it can be hard to tell if blades are rotated straight out from their connection on stump jumper or if they are slightly angled when you're spinning it by hand .
I have one of these cheap Frontiers, RC2084 7ft version. It is what it is. I've gotten better at not backing into rocks and trees and folding the sides into the blades, but my land has so many banks and ditches that uneven ground can fold the sides in too if one backs and turns the wrong way. Being aware of the problem I've reduce folding the sides in from about from 50% of the time I use it to about 25%.
Most likely the bottom of the skirt is folded in just enough that blades only hit at low rpms when blades "droop" from gravity. I suspect at higher rpms, centrifugal force "raises" the blades more straight out to where they the miss the skirt.
Tricks to straightening skirt can involve some BIG pipe wrenches. I found best method is parking it between two trees. Chain one side of mower frame to tree as an anchor (so you don't twist tractor's 3 point hitch) and use a come-a-long attached on the other side to mower's skirt and the other tree to bend it back. It might not look as pretty as it was before when you're done.
