K2636 (problem with BC517)

hi, I made this kit but had T4 (a bc517) soldered backwards.
before finding my error I tried the kit amd found RV1 and RV2 did not have an effect on the motor.
I turned the T4 but without good result, so I ordered 3x new BC517 assuming I had ruined the oother one.

Without checking the transistor that I received from an internet shop I soldered it in and still the same problem. Then I checked the new transistor and noticed this transistor was a 3,3V voltage regulator. The webshop send me one bc517 and two voltage regulating transistors…

Today I soldered the BC517 in and it still does not regulate the motors rpm, so my question is: Could it be the VAC is broken by one of these mistakes I made, and what is the best thing to do to make it work?

Thanks for reading,

Roy

Is it possible to maybe get help from a technician at Velleman? I’m a bit stuck since Januari 2018 with the K2636.

Best regards,
Roy