5v DC motor is dead and I don't know why

[radix-auricularia]

Hello everybody!
This is my very first electronic project, so sorry if this is trivial to you guys or if my explanations don't make sense...
I'm working on an Arduino project to operate a 5V pump (to scare away pigeons) using a HC-SR501 PIR motion detector. My circuit works fine, but I've noticed a problem:

Symptom: The 5V motor/pump worked at first, but after a while testing it, it is now gradually slowing down until it stop completely.
Current circuit:
PN2222 transistor to control the pump.
9V 1A Power Adapter
MB-V2 power supply module
PIR (HC-SR501) output signal triggers pump via resistor and transistor and 5v relay (5pins).
Without the transistor, the pump doesn't work (probably because the PIR also consumes current).

Do you see a problem in my project that could explain the motor being damaged ? I've linked an image of the circuit and the photo of the real one.

[DrDiettrich]

@radix-auricularia

Do you see a problem in my project

Lack of a back-EMF diode across the motor.

[jim-p]

@radix-auricularia

Do you see a problem in my project that could explain the motor being damaged ?

Yes. Running those submersible pumps out of water will destroy them. They MUST be in water.