how durable is the plastic on there products mainly for the shields? i baught a new 2510x line trimmer the begining of the month and broke the shield each time i used it. ive gone through 2shields sofar, had to resort to stripping a throw away jhondeere trimmer i had laying around for the shield. i have babied the shindaiwa compared to what that jd has seen and the jd plastic never broke. is anybody else having the same problem with their newer trimmers?