Today I cleaned and greased the 48" deck on my x350 and also installed a mulching kit on it. Brand new mulching blades and everything torqued to spec. Once I got the deck back on I wanted to test it out a little bit but when I engaged the deck it felt like it was going to shake itself apart. I didn't have time to look hard at it yet but before this I had no issues. Any ideas? Bent or out of balance blade from the factory?