Forerunner 265 gap in HR sensor

I saw your other thread is locked.

I say the dirt is really a non issue.

Probably try loosening the strap by 1 hole. You don't really need to wear too tight for regular daily use.

During an activity, then you can consider tightening the strap.

Can try switching wrists also. I wear on the left for regular daily use and wear on the right for my activities.

Thanks for the comment. 
I did try making the strap looser, but it did not seem to make much difference. Also tried the nylon Velcro strap. 
I wore on my right wrist (normally wear on the left) and after about 3 days the same issue occurred. 

It might not be the dirt, but I do not understand why the older watch is fine. Obviously the straps are different, but the tightness I wear the watches feels the same. 

At the moment if I want to continue wearing the new watch I can really only do it for activities and take it off straight away.
I can do that, but it is a little annoying, I quite like some of the other data and features.  
For example, it seems to make all the data incorrect as the resting HR is not accurate and then messes up some the other readings. 

Probably post the way you wear the watch or let another person judge.

I've seen many tight watch wearing pictures on reddit. Many of them are unaware of.

No harm to try loosening further by 1 hole.