First, how old is your LX90?
Is the ticking affecting tracking in Alt Az mode? There is a major issue with the DEC motor and encoder assembly in some LX90's (newer ones) that affects tracking quite seriously. Check your tracking and see if you can "see" the tick as a bounce in tracking. If not, then we need to look for other issues.
Note that if this is a newer LX90 and your tracking is adversely affected, you probably should contact your dealer about changing out the telescope....the problem cannot be fixed without replacing the entire DEC drive assembly, and repairs at Meade have been far less than satisfactory.
Best of luck