sensors stop working

[mohammadguy]

after the while loop ends and starts again the sensors stop working
the robot starts moving forward but no longer corrects its direction based on the gyro sensor and no longer stops after 15cm.

#!/usr/bin/env python3

from ev3dev.ev3 import*

import ev3dev.ev3 as ev3

from time import sleep

mD = ev3.LargeMotor('outD')

mA = ev3.LargeMotor('outA')

btn = Button()

cl = ColorSensor()

cl.mode='COL-COLOR'

assert cl.connected

us = UltrasonicSensor()

assert us.connected

us.mode = 'US-DIST-CM'

units = us.units

gy = GyroSensor()

assert gy.connected

gy.mode = 'GYRO-ANG'

while btn.any()==False:
	sleep(.09)

def turn(a,d): 
	b = a*50
	c = b*-1
	e = 0
	while e != 320:
		print(str(e))
		e = e+1
		if gy.value() < d:
			mD.run_forever(speed_sp=b)
			mA.run_forever(speed_sp=c)
		if gy.value() > d:
			mD.run_forever(speed_sp=c)
			mA.run_forever(speed_sp=b)
		if gy.value() == d:
			mA.stop(stop_action="hold") 
			mD.stop(stop_action="hold")
	e = 0

def forward(f):
	while us.value() > 150 and cl.value() != 1:
		print(us.value())
		print(cl.value())
		print(gy.value())
		mD.run_forever(speed_sp=100)
		mA.run_forever(speed_sp=100)
		if us.value() < 150:
			mA.stop(stop_action="hold") 
			mD.stop(stop_action="hold")	
		if cl.value() == 1 or cl.value() == 3:
			mA.stop(stop_action="hold") 
			mD.stop(stop_action="hold")
		if gy.value() < f:
			mD.run_forever(speed_sp=45)
			mA.run_forever(speed_sp=-45)
		if gy.value() > f:
			mD.run_forever(speed_sp=-45)
			mA.run_forever(speed_sp=45)
gy.mode = 'GYRO-RATE'

sleep(0.09)

gy.mode = 'GYRO-ANG'

while True:

	forward(0)

	turn(1,90)

	forward(90)

	turn(1,0)

	forward(0)

	turn(1,-90)

	forward(-90)

	turn(1,0)

	forward(0)

	turn(1,180)

	forward(180)

	turn(1,0)

[dlech]

What is the date code stamped on your gyro sensor? e.g. "19N3"