Just found this article about problems with the rear wrist hrm plastic on a 235 - https://forums.garmin.com/forum/into-sports/running/forerunner-235-aa/137627-slow-deteriation-cracking-of-heart-rate-monitor-plastic-on-back-of-watch.
I've got exactly the same problem with the wrist hrm on the back of my Forerunner 735XT.
Bought this watch in July 2016 and it has been working without any issues... lately I've had a couple of runs where I've started the activity and then noticed during the run that the distance is not being recorded although other fields pace and time are displayed. I always let the device get a GPS fix and then wait a further 30-60 seconds before starting. If I try and save the activity at the end the 735 hangs on 'saving' and can only be brought back to life by resetting. Also I am unable to go back into an activity [it will immediately jump to 'saving' and hang again] until I've performed a full factory reset. Weird. I'll keep an eye on this.
Anyway, back to the original point. I've noticed the cracking on the wrist hrm and I only run the watch under water after use to clean sweat off it and dry it off immediately. I don't used any cleaning agents or IPA. It might sit with some sweat on after, for example, commuting to work until I've had a shower/wash but that's about it. I'm very careful with my devices and it hasn't been dropped or bashed or anything similar.
Anyone else getting the same issue?
I am a bit worried about water ingress although this doesn't appear to have happened as yet.
