Good afternoon Geneva,
A deformed beak whether it be extremely overgrown or is deviated in it's growth can definitely cause prehensile problems during feeding! The fact that you say your conure is beginning to lose weight that you can actually appreciate is a big concern to me!
At my practice, we see all of our avian patient's EVERY SIX MONTHS!! By this point in your pet's life, you should have established a solid relationship with an avian veterinarian to keep your conure up to date on husbandry, nutritional, and metabolic problems that occur with your pet. I realize that you say you do not have an avian vet nearby, but I cannot stress enough how important it is to find one , and then to make the effort to get your conure in for routine veterinary care once you do!!
Weight loss in avians CAN definitely be attributable to beak deformities, but it can also be due to intestinal parasitism and metabolic and systemic disease states that have gone undetected due to lack of owner awareness and veterinary preventive care.
To answer your question, YES, the beak can be trimmed back, but for a layperson to be able to discern when enough is enough can be a problem. In my practice, we usually use a DREMMEL hand tool to finely shape and contour the tip of the beak into an acceptable blunt point. Obviously, the pet must be restrained properly to prevent injury to either the pet or the handler in question! Not all pet birds appreciate this technique, and I must recommend that you allow a professional to handle this task for you!!
In the interim and if you truly think your pet cannot eat enough due to problems grabbing his food, and while you are trying to locate an avian vet, I would offer your conure a slurry of pateed veggies. You can buy stage one Gerber vegetable medley, squash, green beans, carrots...anything that your conure may like. You can syringe feed it slowly if your conure accepts it willingly, or you can place it in a container that your conure can access easily with it's beak. You can also blenderize your conures pelletized ration with warm water to make it into more of a slurry for your conure to eat. This is only made as a shortterm recommendation to get your pet through until the beak can be addressed! Ideally , your conure should be able to mouth and prehend all of the normal solids, fruits, seeds, and nuts they are typically allowed to be fed!
I must add that if the beak is growing abnormally, that the odds of an underlying metabolic bone disease or nutritional deficiency becomes quite likely. In particular, if your conure has not been on a veterinary approved and monitored dietary plan, than your pet could be malnourished and suffering from either metabolic bone disease or hypovitaminosis A and calcium and phosphorus deficiencies.
To be safe and to get your pet "caught up" on it's veterinary care, you should find a vet as soon as possible!!
http://burgebirdservices.homestead.com/beaks.html
http://www.ehow.com/how_9303_trim-birds-beak.html
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Best Wishes to You and Your Pet!
Dr. Jodi L. Smith
Dr. Jodi L. Smith, over 13 years of clinical and surgical expertise in all species, with special emphasis on exotics, pediatrics, dermatology, cardiology, and geriatric medicine. Your pet's health and well being are my first concern.