That time/value dial is easily replaceable. The part description, from the 2400 Service Notes:
01231367 ROTARY ENCODER EC16B24204 (L=15) (W/N&W)
The same unit is used in the VS2000. Roland sold me the part directly, and it is a pretty simple job to replace it. IIRC, it was about an hour start-to-finish. There are only three or four solder points.