If the snare pad or tom pads on the Roland TD-02K or TD-02KV tilt out of position while playing, even after you've firmly tightened the bolts on the pads themselves, the pipe holding the pad may be sliding. Firmly retighten the bolts and knobs on the holders that stabilize the center pipe or arms, not just the ones on the pad.
Note: Vibration from extended, hard playing can gradually loosen bolts and knobs over time, causing pads to tilt out of position. If this happens, readjust the pad positions and firmly retighten the bolts on both the pads and the pipes.