This can happen for a number of reasons from simplest to most complex.
1) Your Glue wipe has glue deposits on the face that sits on top of the glue wheel and needs cleaning.
Page 30 in the CG-1 User Manual has some example photos.
2) Your Glue wipe is not correctly aligned on the top of the glue wheel allowing glue to leak down one side.
Please email [email protected] to raise a ticket and receive details of how to make this adjustment.
3) Your glue wipe has become badly work and needs replacement.
Please email [email protected] to raise a ticket and receive details of how to replace a glue wipe.