Ennviro ef2 Fan motor shuts off once in a while

[karayj]

The last month for no reason I cna think of after 1 hour of running or 4 hours or 45 min the blower motor shuts off.
This has only happend 4 times in the last 30 days. The unit is about 4 years ol keep cleaned and maintiained.
What should I look for ?

 

[Wood Heat Stoves]

MOD, pls move to pellet mill..

OP, do you have the service book? i believe it is avail at enviro.com
if not, pm me for a copy