Python3 asyncio - running two servers in own thread

I have my servers classes inherited from BaseServer:

class BaseServer(object):

    def __init__(self, host, port):
        self.loop = asyncio.new_event_loop()
        asyncio.set_event_loop(self.loop)

        self.instance = asyncio.start_server(self.handle_connection, host = host, port = port)

    async def handle_connection(self, reader: StreamReader, writer: StreamWriter):
        pass

    def start(self):
        # wrapping coroutine into ensure_future to allow it to call from call_soon
        # wrapping into lambda to make it callable
        callback = asyncio.ensure_future(self.instance)
        self.loop.call_soon(lambda: callback)
        self.loop.run_forever()
        self.loop.close()

    def stop(self):
        self.loop.call_soon_threadsafe(self.loop.stop)

    @staticmethod
    def get_instance():
        return BaseServer(None, None)

I need two servers running in own thread to processing requests in parallel. But when I trying to run them as needed, only first server is running. Below how I run them:

if __name__ == '__main__':
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)

    async def run():
        pool = ThreadPoolExecutor(max_workers=cpu_count())

        await loop.run_in_executor(pool, Server1.get_instance().start)
        await loop.run_in_executor(pool, Server2.get_instance().start)

    loop.run_until_complete(run())

1. What am I doing wrong? How to run each server in own thread?
2. When asyncio.set_event_loop is calling from def __init__ I got next error:

RuntimeError: There is no current event loop in thread 'Thread-1'.

But if I remove asyncio.set_event_loop from def __init__ and move it to def start error disappears. Why this happened?