Why does my Sligh 124BL chime irregularly

by JB Peterson
(Sugar Land, TX)

My Sligh 124BL chimes the hour in an irregular fashion.

The hour always chimes but only 3 to 6 chimes.
The hours 7 to 12 NEVER chime correctly.

The 1/4 hours chime correctly and the clock keeps perfect time.

Any thoughts regarding the cause for the irregular hour chime would be appreciated.