When I bought my 4511 table saw, I found it was shipped without one of the lock knobs for blade tilt/hight. I e-mailed customer service about this via my "dashboard", but recieved no response for six days. I e-mailed again. Three days later I recieved a response to the first and then thre days later, a response to the first. Both were from "One World Technologies" and both were "canned" responses telling me that if I wanted parts, to call the parts dept. I did, and was told the part would be on its way immediately. Two months later, I decided to order a new knob from Amazon.com. Got it two days later. BTW, when attempting to install the new knob I discovered that the tilt shaft had been cross-threaded and I had to re-thread it and now it is kind of buggered up, but I guess that goes with Chinese Mfg! Yes, I know the shaft is M8 x 1.25. GREAT CUSTOMER SERVICE, RIDGID AND TIM BEASLEY!