Answer: First things first... regardless of what cleaner or solvent or method you use, TEST TEST TEST on a small out of the way area of the plastic before proceeding further. It is almost impossible to guarantee how any particular solution will work with any particular plastic without testing first.

 

Second, please review the related article (see below) re cleaning a model in general. There are some relatively common but very scary cleaners out there that can really make a mess out of your model.

 

Third, please review the related article (see below) re cleaning POLYCOTE ECS. This method has been found to work well on most canopies and clear plastic formed parts as well. Remember TEST TEST TEST.

 

Lastly, if the blemish will not go away, you may want to consider replacing the part. Please review the related article (see below) about replacing canopies and formed clear plastic windows. Before launching into a replacement operation we suggest considering if it is worthwhile. Blemishes in clear plastic are common and you may replace a canopy today only to have a new scuff mark or blemish again tomorrow. Enjoy your ARF model and your RC hobby and confine the replacement effort to when it is really necessary like when you have a hole or crack.