These are the possible reasons and solutions

E1	Stop up switch is not being activated - a number of things could cause this - up down motor, tangle in string, UD fuse, broken wire
E3	String stuck lowering - not a common error but check for the same things as E1, but especially string tangling
E9 & siren	Actually a backwards e and a 9 is related to the sensor - it may be something blocking the sensor, or the sensor needs adjusting or the pin JP11 has come loose. You can temporarily disable the sensor if while a replacement is sent. To do this put pins 1 and 4 on bank to back to off and reboot, until the prize sensor arrives.
E9	The coin meter is faulty or disconnected. Check the back of coin meters or plug J7
E7	Choc machine tilt tray error - remove false base and metal cover to inspect mechanism
Ep	Choc machine slider tray error - switch at back of tray not activating