This is a reoccuring problem with this product.
Use a 22 or bigger, and fill the syringe then draw in some air. Immediately change needles, push the air out, and inject QUICKLY. (the clog is usually in the needle itself.)
Thinning with sterile water will help, but you still need to change out the needle. Also, coating the dart and needle with a little oil from another steroid will work.
As you get to the bottom of the vial, the shit really gets thick and clog prone.....at this point, you will have little choice but to thin it with something.
Suspension works great, but is a real hassle. You need to inject at least daily, or even several times a day due to the extremely short half-life. I often kick off a cycle with one cc a day for 20 days while the slower tests reach proper serum levels. Few of us last longer than 20 days, because of the soreness. My advice....stick to the glutes so your workouts are not affected.
I have found this clogging problem with every brand I have tried.....except for some fake shit from canada.