should be able to find in any bike shop.  you could try RAD through customer service.  Possibly Area13 could sell and lace one up for you. 

from your photo it is the front wheel.  I suspect they hit the brake caliper.  It may be out of alignment. 
If you rotate the wheel watch the caliper as the wheel turns.  You can manually adjust the caliper by pushing or pulling depending the alignment need.  Once done make sure you find a clean clothe to whip off your hand oils you put on the caliper.  This is what seems to be your problem that the caliper is pressing on the brake pads. 

could be out of balance.  may have bent spokes and causing brakes to rub.

It does sound like the motor has an issue.  Is motor cable connector on the left or PORT side?  If so you can't open the motor up to check or repair.  Have you tried flipping the bike upside down to diagnose?  movement of the wheel....

You could try AREA13 for a replacement motor and they will even help with diagnosis.  They respond fairly quickly. 

Not sure why it worked before and now after shortage it doesn't work. 

Best of luck.  Let us know what comes of the motor issue.

yes new controller is more power but I have already gotten used to a different bike with tons more power. so that's why i say some extra power. I have the upgraded controller with a new motor and was very pleased until the bike needed a new battery.

Area13 should have that motor and may have a true 750 bufang motor as well.

you may know but it is a fairly simple swapping of the motor to into your wheel.

I is most likely the controller.  The rectangular box on your bike.  Area13 has the upgraded version giving you a little more power and a new color LCD screen.

Check out Citizencycle on youtube.  He is unpaid and has done several reviews on different ebikes including Himiway.  He has done upgrades on many bikes as well.  He does range tests and motor performances too. Maybe that will give you more guidance.   

I have a Rover 5 and a Wired step thru.  The wired has a larger battery much more powerful.  It is a larger bike but rides nicely.  The Rover is probably a better size for me.  If I had to do it over again, I would just order a larger battery for the Rover.  I already have the upgraded controller and upgraded True Bufang 750 watt motor on it.  A few other tweaks I may make is increase the front COG larger with more teeth and raise the handle bars.  Of course the battery larger 52watt and 20 plus Amp. (52 will only work with upgraded controller)  Already know the battery just deciding if I should invest.

I saw on youtube of a guy who had a semi battery bike NON RAD....anyway he bent his frame because the structure is weakened with the new design.  It was a step thru bike.

The easiest option you have is to replace the controller.  If you are going to do it, then go with an upgraded controller to 35 amps. It will give you more power and some extra speed.  Area 13 has them usually in stock.  You will also get an easier to read color LCD screen.

all original equipment and electronics?

do you use lots of throttle?
is it difficult to remove the battery?

if yes to first question then yes to the second, it may mean that the wiring may have melted.
report back and I can let you know what happened to me and how i corrected it.

Have you installed an different headlight?  Aftermarket headlights can burn up Rad controllers.

Hopefully it is under warranty and you receive a new controller.  If not and you have to have lights you can either go with battery operated lights or a new controller.  If you decide a new controller, I suggest you upgrade to a 35amp for more power and color screen. 

Area 13 carries the upgraded controllers and the screens as a kit.  They do sell out from time to time.

One guy on this forum bought a used partly functioning controller and salvaged parts from it to make his work.  Inside the controller there are 2 small boards that control either the front light or the rear.  They are the same part for either light.  He replaced those to make his lights work.

do you have the original light that came with RAD bike?  some aftermarket lights can burn out the new controllers.