Do I need new bolts or fasteners to install this?

The assembly uses factory mounting points, so your existing hardware should work. Inspect bolt condition before reinstalling — if any are stripped or corroded, grab replacements from the hardware store while you have the door panel off.

What if the window doesn't operate smoothly after installation?

Check that the regulator track inside the door is clean and free of debris. Lubricate the track with a light silicone spray before final testing. If the motor still doesn't respond, verify electrical connections are seated firmly at the motor harness.

Can I test this before fully securing it to the door?

Absolutely — connect power temporarily and cycle the window up and down a few times to confirm smooth operation. This catches any defects before you reassemble the interior panel.