The best advise that I can think of is to remove the side plate, dis-assemble, clean the entire gun and all internal parts, re-assemble (leave off side plate) and look to see what is binding. Shinny spots and rub marks are what you should be looking for.

Other than that, help is hard to give without seeing exactly what is happening. It could be something as simple as hardened oil or grease, a bent or misaligned part, but if you are not comfortable & familiar with taking the gun apart and putting it back together, a trip to the Factory or a qualified GS might be in order.

Chief38