Boilermate II Timer vs PCB

Hello all. I have been scrolling this forum to see if there was an obvious answer but am struggling.
We are having two issues from the boilermate 2 and not sure if it is one part causing the problem.
Getting the dreaded buzzing what seems to be every 20 mins or so, which reading all the posts, is probably the PCB.
In addition, the mechanical timer is stopping randomly through its 24hour cycle meaning the heating is not kicking in when it should. Could the buzzing and timer stopping be related, ie both parts are goosed or could one be causing the issues over the other?
Any help is appreciated Andrew

The mechanical times is worn out, as a mechanical device the mechanism eventually wears out and does things like stopping or of course gives up completely part number is probably XB215 (available new from Keep the Heat on).  The buzzing is one of the two small pcb's as you rightly surmised.   It sounds like it might be the pump drive as it is repeating at a fairly regular interval,  the pump drives job is to periodically run the heating pump to help stop it sticking when not used for long periods such as through the summer.  The other pcb with  the yellow tube on it allows the boiler circulation pump to run on for about 3minutes after the boiler goes off to remove any residual heat from the boiler.  This one is on whenever the boiler is so you would expect the buzzing to be longer etc.  That said once one of these pcb's start adding up the other will not be far behind.  You can buy new ones from companies like Keep The Heat on, part numbers XB104 & XB041 (yellow tube one).  I can also provide an exchange service for the pair (or one if needs be) please have a look on my website for details.  Regards Murray    See bottom of purchase page for exchange option - https://murraymartin.yolasite.com/purchase-page.php

Thanks to Murray, I used his exchange service.

Ordered both PCB's, they arrived next day. I fitted (very simple switch over) same day and returned faulty parts and refund was in my account. All sorted in 3 days - Perfect