Let me preface this review by saying that I have never serviced my unit before. And short of clearing out my pool's basket and skimming it, I don't know much about servicing, or have much inclination to service my own pool.My Stayrite Max-E-Therm 400 was short cycling (heater turns on and off constantly before target temperature was reached). I also have a salt system that generates chlorine and the salt plays a factor in the early deterioration of the thermal regulator. After a quick search online and after reading the other review here, I decided to buy this part and attempt the repair myself as my new pool technician does not service this unit.The instructions that come with the part are pretty good. It has a simplified diagram from the owner's manual that pinpoints and magnifies the location of the thermal regulator. It also has step-by-step instructions on how to replace it.Believe me and the other reviewers here. If you can unscrew a plug and screw it back on, then you have the skills to change this part. It literally took me less than 5 minutes. After doing it once, I could probably do it again in less than 2 minutes if I had to.A few things to keep in mind: (Refer to the photo. The smaller plug on the bottom is the drain plug. The larger one above is where the thermal regulator goes) You'll have to unscrew and screw back in 2 plugs, there is a smaller drain plug under the thermal regulator plug that you should unscrew and remove first. If the system is off or if the water is no flowing into the unit, there will be maybe about quart of water that will leak out. Then, use the shaft of a screwdriver (see image) to unscrew the larger plug that contains the thermal regulator. You'll see a little more water drip out as you are unscrewing. Be mindful that you're removing a plug that is compressing a spring. So, keep some inward pressure on the plug as you're unscrewing so that you don't get a jack-in-box surprise. Once the old thermal regulator and plug are removed, you're ready to put the new one in. Place the spring in the plug as shown in the directions (the spring goes into the inside of the plug and the complicated-looking head mechanism sticks out and is inserted first). Press the plug in and start screwing it back on. Apply a bit of inward pressure as you will be compressing the new spring. Finally, replace the drain plug you removed first. Now, start the water flow. Depending on your system, you can do this by either by turning on the pump or opening the valve. Once your pump gets up to speed, turn on the heater. Your short-cycling issue should be resolved. The heater should be functioning normally. You can now brag to all of your friends and family that you repaired your Stayrite Max-E-Therm 400 all by your lonesome.Go grill. It's Miller Time.