I see them for sale on eBay from time to time.  Unless you are concerned with customs, you might give eBay a try. 

I recommend Tannus Armor inserts.  Since I have installed them I have never had a flat.  But without them I had at least 4 flats on the rear wheel and I was tired taking the wheel off the back.  It is a pain in the butt.  The front tire I have never had a flat and I have over 4000 miles on it.  I was waiting to replace the tire on the front to add the Tannus.

Probably but I would consult Area13 formally Bolton Bikes.  They will have the best answer for you. 

I would say if Rad wants to charge for something like that, but aftermarket.
Aftermarket will probably be better quality anyway.

all the more reason not to have a semi integrated battery. 
Yes they looks nice but not worth the hassle if you need to replace with an aftermarket battery.

i would say that is excessive overkill.
i charge mine inside the house but on the kitchen counter. 
i also use a timer that shuts it off after 5 or so hours.
never had a battery problem with my Rad Rover 5 and over 4000 miles.
charge after every use probably 300 days a year.

Possibly the wiring harness.  Maybe has a break in the line some place?  I have also read some have brake sensors causing power problems. 

If you stay with the Rad Brand, go with the Rover.  The Expand can be prone to wiring issues from the multiple folds.  The Expand is still very heavy and bulky.  If you have a truck, you have the room or you can get a motorcycle rack off ebay for $100. 

I would stay away from the expand.  They have been prone to wiring failures.  Probably from the multiple folding of the bike and wires.  They are still very heavy and bulky.  Is your reason for wanting it to transport it easier or storing it? 
Good Luck

I had a large basket and it was too big.  I rarely filled it.  It was also in the way of the seat so my post wouldn't spring in to action.  You can mount it sideways but I wasn't interested in that.  I personally would stick with the small basket. 

You should add to the post the problem rather than the video.  I didn't know there was a video until after I logged in. 

Which model Rad do you have?  Only the controller has been replaced?  Maybe some settings on your display that need to be configured.

The distance between my magnets is much greater than yours.  Probably 3mm at least on mine.

I assume you cleaned the magnets and sensor....Possibly a bad sensor....mine when on turns red.

Hopefully you sort it out soon. Good Luck.

you should list it on NextDoor website, Facebook market place, and maybe craigslist.  Today I listed a Rover and within one minute I sold it on NextDoor.  Usually Facebook is the best place for selling.  Craiglist is last these days.  Good Luck.

Yes Area13 has the controller that will work for the RadCity.  It will give you a much needed off the line torque. 

Is the new motor that same specs?  Because if it isn't the controller may need to be upgraded.
But of course a nick in the wiring could very well be the problem.

you can check craigslist and facebook marketplace for Rad prices.  They have a wide range depending on model and mileage.  I bought a used Rover 5 last summer for $700 with 600 miles on it.  I cleaned it up and sold it for $800 to a friend.  Then I bought another Rover Stepthru for my wife for $900 with 300 miles.  The prices are all over the place.  Some are trying to sell at new retail price for used.  Area 13 will have a replacement controller that will boost your top speed and your take off torque.  My current Rover 5 has 4000 miles with an upgraded controller and higher wattage motor.  Very please except battery life.  If you are thinking new bike then consider Wicked.  It has all the upgrades the RAD doesn't stock.  Good luck.