Hi.the controller as It's own box on the seat tube like you say. Soldering i can do. I will start looking on the Internet for a new kt controller and display kit and yes it is a 9 pin connector. Thanks Steve
There are a number of different ones that you can get from Topbikekit directly or from their Aliexpress listings. You can get them with the waterproof connectors or block connectors. You should get the block connectors for several reasons: Firstly, you have a box to enclose the controller; secondly, it's easier to test with a meter if something doesn't work; thirdly, the pedal sensor is often wired differently, so, although it fits, it doesn't work; fourthly, very occasionally, the sequence in the motor cable doesn't match the controller, so you have to swap pins on the connect, which is not possible with the waterproof ones.
If you have low powered lights, they'll probably work from the LCD, but IMHO, it's always better to wire lights directly to the battery via a switch and fuse because the wires are easily damaged, and a short can wipe out your controller. Alternatively, use lights with their own rechargeable battery pack, which gives the possibility of much better lights.
You will need to buy a motor cable of the correct type, any KT LCD except LCD1 and a throttle. The throttle can be setup to give max speed 4 mph, and max power as an override for the pedal assist, which is both useful and legal. You can get a pedal sensor too, which is guaranteed to match and work, but you have to remove the BB and or pedal to fit it. Bear in mind that there's a high probability that you'll have to cut the wire on your present pedal sensor to make it work, though you might be lucky.
Finally, you have to do something with the brake switch wires. At the moment, they plug into a harness with connectors near the handlebars. You'd need to run a cable down to the controller if you get the one with block connectors. If you get the controller with waterproof connectors and harness, you might be able to plug in directly, but you need to check how many pins in your connectors, as there are two and three pin versions, and if you have three pins, they might not be in the correct sequence.
That all sounds a lot, but you can do it all in about an hour if you understand basic wiring and can solder. The end result is a much better control system, so we'll worth the effort.
When you get a 36v/48v dual voltage one, when your 36v battery expires, you can replace it with a 48v one to give more power options and better hill-climbing without having to do any more work - just slot it into the cradle.