Rockola 1454 amplifier mute

Hi
Just recently and without warning my 1454 does not mute the amplifier before placing the tone arm on the record, this is causing an audible crackle as the needle passes over the cleaning brush.
When the record ends the mute appears to work, I have re set both micro switch 3 and 4 and cams which are situated to the left of the gripper assembly, both are working ok the juke selects and plays the record with issues at all.
I have also checked and re set and positioned the cam limit switch to no avail.
I was advised to check the mute relay in the amp, but there doesn’t appear to be one in there, please see attached amp image
There must be a mute circuit somewhere that is malfunctioning but I don’t know where it is, or could it be a bad earth
Like I say the jukebox plays great and I have no issues apart from the noise as the tone amp passes over the cleaning brush
Thanks in advance
Regards
Andy

Hi Andy

Please check the «No.5 Grip Cam Limit Switch » (see manual). One of the blade contacts is responsible for the mute circuit. As another possibility you can check also the no.7 relay contact within the control box.

Might be these contacts have to be cleaned or adjusted.

Regards
Eddie

Hi Eddie
Thanks very much, I have had a good luck at the no 7 limit switch which does appear to be working ok, but I’ve not looked at the cancel relay in the control box, hopefully it’s that which is causing the issues
Thanks again
Regards
Andy

Hi Eddie

I have rectified the issue thanks, it was the grip cam limit switch, on initial viewing it did look ok but I managed to ease the switch out to take a closer look at all the contacts, some looked oxidised so I cleaned all and it’s working fine, your help is greatly appreciated thanks again
Regards
Andy