Since there is no official "Ucom" website, you can use these verified third-party driver archives that host the specific vibration-enabled drivers for this model:
Inspect the device:
After installing the driver, restart your computer and test the joystick to ensure it's working correctly: ucom uc js704s2 usb joystick driver win 7 download link
Before downloading, ensure you trust the source and have an up-to-date antivirus program to scan the file for any potential threats. Since there is no official "Ucom" website, you
Finding a direct, official download for the Ucom UC-JS704S USB Joystick ucom uc js704s2 usb joystick driver win 7 download link