
Leigh.... I think the concrete type perches work better than the sandy/sandpaper type - plus easier on the feet IME.
I have used nail clippers (be ever soooo careful not to clip his tongue) - this is a job best done with 2 people, one to properly restrain the bird and the other to do the trimming. A dremel tool is used by the vets I heard, have not tried that myself but may soon (I never get over-grown beaks btw).
Great that you found a shop you trust that practices strict hygiene & disinfects everything (including the A.C. ducts on a periodic basis at least).
Btw, beak over-growth can be caused by a high protein diet in some types of birds - so check that. The beak should remain in proper condition without trimming, in birds that are maintained on a healthy diet supplemented with fresh fruits & veggies, exposed to adequate periods of sunlight, allowed to bathe regularly & provided with hard woods to chew.
Case in point: Once I made a sympathy purchase of a canary with bad scissor beak. I put it in long flight cage with cuttle bone, a couple concrete perches (in addition to other types), healthy diet and the best F.S. Lighting I know of (IMO) and a couple months later his beak was perfect - without any trimming from me.