Do you have part number for the 35A FET and 30A 600v(prv) Ultra-Fast kickback?Hi There, There is only one main switching FET on that unit, which is mounted to the heatsink/frame of the controller with a metal bracket, near the white current resistor standing up on the board, maybe marked 1.75hp on the side, which related to the factory stamp for the current sense resistor value to install. It may have been mentioned earlier, that if the main FET is blown or shorted, that kickback diode next to it will also be damaged. Both parts are a bit sketchy in this design and should be updated to a 35A FET and 30A 600v(prv) Ultra-Fast kickback, which also must stay isolated from that case or things will rip apart at power up. That motor rail resides on a "Hot Ground" and shorting the kickback to that case will release trouble in a huge way. Finally, if these 2 parts are ripped/shorted/blown, there will most likely be more issues long the drive-chain, thru the predriver circuits usually, and this is an all discrete design, one I cannot advise others to play with. I have spent at least a decade repairing these style of controllers, and I can tell you with certainty, if a single thing is missed during bench troubleshooting, a servicer can expect a large rip and smoke from the controller at full-load testing. I am used to it, most other would not be, nor would they maybe be prepared to power-down a hot-bench in a fast way to clear away that blast zone ;o) These boards, upper and lower of the controller, must be pulled apart to service, which is a tender job as well, as one missing or intermittent header pin, 40-connection points, or connection between boards will again cause major troubles. This is one of the "can't suggest folks try this at home" units. That motor rail bulk voltage sits at +165vdc for US models, and that bites terribly hard.