I had a Redline 17.5 show a lack in power. I took a close look at the motor and realized the can and sensor housing started to separate. This separation will cause the bearings to come out of alignment.
Look closely at the rear of the can in the area where the label is. You will notice a seam in the can. This seam should be even and tight all the way around. If not, you popped the two pieces apart. These two pieces are held together with a two part epoxy after a few hard crashes they can start to separate.
If the motor is beyond the factory warranty, fear not, it can be fixed! Just need some basic tools, elbow grease, and JB Weld!
First remove the three screws holding the plastic cover on the back of the motor and remove the cover.
Next, carefully unsolder the three motor tabs from the windings. Using an old cap off of a spray can as a stand helps. Just poke a hole in the middle of the cap 1/8in diam and set the motor shaft down inside.
To unsolder the tabs, apply heat with the iron, then as the solder melts carefully lift the tab off the motor with tweezers or needle nose pliers.
Once the three tabs are off you can remove the fiberglass insulator then the sensor array. Lift the insulator out of the motor then turn the sensor array so the three aluminum tabs can slide out of the three slots in the aluminum housing.
Third step is to make alignment marks on the housing and the can so you can re assemble them properly later. I used an x-acto blade to scribe three small marks across the seam and the housing.
Once you make the marks. Carefully pry the housing away from the can. Depending on how far they were knocked loose, you mat need the help of an x-acto blade, or a small slotted screwdriver. Once you get started they will separate quickly.
After you remove the housing from the can, you should notice the clear epoxy that was used to hold the two pieces together. Carefully peel off all the old epoxy around the inside lip of the can as well as any remaining epoxy on the housing.
Once all the old epoxy is cleaned off, prep the bonding surfaces with a gray scuff pad (scotch brite) and wipe clean with some alcohol or motor spray on a rag.
Mix up some JB Weld according to the instructions on the package, and apply a coating to the inner lip of the can as well as the area on the housing going into the can. Make sure to get a nice even coating. I like to use a toothpick or an old scrap of lexan to mix and apply the JB Weld. Join the two parts together as soon as you are done coating them, paying attention to the alignment marks you made earlier. Make sure the seam between the two parts are tight and even.
Wipe off any excess JB Weld from the outside of the motor. Double check the alignment marks you made, then let the whole thing sit for 24-48 hours to fully cure.
Once the JB Weld is cured. Simply re assemble the parts in the opposite order you removed them. Hope this helps.