Over grown beaks can be associated with liver disease, and the bird can look healthy on the outside. I would urge that you find a vet who has worked with birds and is comfortable with them. Power tools are the best to trim an overlong beak quickly, painlessly and efficiently, but they must be use by people that know what they are doing. If he was my patient I would run some simple blood work as well.
If he will let you do it, try smoothing it down with a fresh clean emory board. Some times the glass-type nail files work pretty well, but you need someone to gently restrain him while you file. That is why most people opt for a vet to do the work.
here is a vet from the AAV website, perhaps he can refer you to a local vet:
Last updated: 11/6/2015
*****br />Unit 212MemphisTennessee
38103 United States
I really must stress that you need a bird-experienced person, and not just a vet who advertises that they care for birds.
The best referrals are word-of-mouth, so check with several non-bird vets, the humane society, parrot rescue groups, bird clubs, etc. for their input. Here are some links to TN organizations, perhaps someone in your area can recommend a vet:
Many times, adjusting the diet (see below), providing 12-14 hours dark, quiet uninterrupted sleep at night, and lots to do will help.
Here are a few suggestions that I give everyone: important!
The following guidelines help with basic issues such as nutrition, obesity, good immune status. Surprising how the following can make a bird healthy, and how infrequently birds are ill if they are on the following regimen. No amount of medicine is going to work if the birds' basic needs are not met.
great resource links:
Birds should be on a high-quality, preferably prescription, pelleted diet: I prefer High-potency Harrison's
TOP (lovebirds really like this brand)
In addition, they should be offered dark leafy greens, cooked sweet potatoes, yams, squash, pumpkin; entire (tops and bottoms) fresh carrots and so forth. No seeds (and that means a mix, or millet, or sprays, etc. etc.) and only healthy, low-fat high fiber people food. A dietary change should be closely monitored and supervised by your avian vet.
Birds should get 12-14 hours dark, quiet, uninterrupted sleep at night. Any less and they can suffer from sleep deprivation and associated illnesses. They should be covered or their cage placed in a dark room that is not used after they go to bed.
The cage material should be cleaned everyday, and twice a day if the bird is really messy. Paper towels, newspaper, bath towels are ok. Never use corn cob, sawdust, wood chips, or walnut shell.
Food and water dishes should be cleaned and changed daily. Keep one set cleaned while the other is in use.
Fresh, perishable food should be placed in separate food bowls. Remove fresh food from the cage after a couple of hours to avoid spoilage.
Change cage papers daily, and clean the grate and tray weekly.
Clean food debris or droppings from toys and perches as needed (which can be as often as once a day).
Grit is not necessary for birds, and will cause digestive problems and death. The best sources of minerals (and vitamins) are leafy greens. Never give grit, gravel sandpaper or cement perches. A bird will eat those to excess when it is not feeling well or if there is a nutritional deficiency. They do not need it at all (an old myth from the poultry days, even poultry do not need it). It can cause an impaction and lead to serious or fatal consequences.