What Browser are you using?
I seem to remember I had this a while back and I think it had something to do with the amount of spamming I was doing. Since I stopped its been fine
Also, if your going to fit yourself and your existing zorst has been on for a long time, pop in to your local garage and get them to loosen and tighten back up all the nuts. Otherwise you will need a blowtorch or something to heat them up
I got one in the used car lot, if you do one race in the licences, then exit, a whole day has passed and you get new cars in the lot, just keep doing that until you see one appear.
I am up to extreme and not won a truck yet