Please do not epoxy the end and top of your motors. That is considered a motor modification, not allowed under NAR rules.
The E9s are well known for CATOs. That is probably why they were taken out of production.
E12s and E16s not nearly as much, but any motor can CATO.
This problem of the nozzle blowing out seems to be fairly recent.
In the future, whenever you have a motor CATO please consider filing a MESS report (
https://www.motorcato.org/).
This will document and compile the failure into a statistical survey. Unfortunately the list is not available to the public. Reason given is that simply releasing the numbers does not show the RATE of failure.
Also consider filling out Lakeroadster's informal form here:
https://www.rocketryforum.com/threads/suspected-bad-motor-list.150501/#post-1852295
Also will not show the rate of failure lacking figures on the #s sold, but it's the only thing we've got, and is strictly voluntary. Cheers.