Don't take me wrong, if a blade is bad it will let you know and by all means do NOT use it. It will cause much wear on things and possibly disaster at some point and time.

I'm using glass blades from Airborn Models on my Venture and they are working very well and best of all they are $28 a set.

Here is a link to the page with the blades if your interested.

Here is the one's I purchased:
Fiberglass 550 mm symmetrical

http://www.airborne-models.com/

Go to this web site, then go to the bottom of the page and look on the left side for this:

Plane Parts and Accessories
[ Plane Parts ]
[ Accessories ]

Click on Accessories, go to the second page on the very bottom.