It looks like your lens is of a recent manufacture ( within the last 10 years ) so it should still be repairable by Tamron. If it doesn't zoom correctly/smoothly then it needs attention by someone who knows the complex nature of the mechanics. My first option would be to contact Tamron to get their advice on repair, maybe they can fix it or they might recommend a repair agent in your country. It looks like a quality lens that would be worth the cost of repair unless the cost is outrageous.