cutting wood.

i use it to cut logs. (a chainsaw would be the best tool, but dont plain on having kick back and cutting my head off, so i've bee using a safer reciprocating saw.

I have had 4 reciprocating saws in the last 4 months. 2 skills a hyper tough and a wen. After cutting wood for 1.5 hours a day for 3 weeks straight, everyone of them, in the end start knock, then plastic starts melting out from inside.whats going on here??? Then i have to return them, because the quiet working.