If the difference in the available light is considerable (less light where it was), that's probably a contributor, if not the sole reason for leaf loss. This tree tolerates very dry conditions well, so water only when the soil is dry at the drain hole. Leaf loss could be from overwatering - judging by what you offered - or accumulating salts in the soil from watering in sips or over-fertilizing. It's hard to say. Remedial: I would unpot the tree & look at the roots. If any are black & mushy - it's indication you're over-watering. Trim the offensive roots back to viable tissue & repot. If the roots are healthy, flush the soil thoroughly and repeatedly to remove salts. Fertilize with 1/2 strength of something like MG 24-8-16 or 12-4-8. Foliage-Pro by Dyna-Gro would be excellent because it has all the secondary macronutrients along with a full compliment of the micronutrients. It's also possible your tree has an insect problem, so inspect carefully - especially for scale. Bio-pathogens are also a possible problem. A safe treatment for both insect infestation and fungal problems are applications of cold-pressed neem oil at 2 week intervals. Questions? Al

You don't indicte which side of the country you are on...Greer in Oregon has them listed; ordering from them is safe. Before replacing your lost plants, have you determined why they died so the same mistake doesn't happen a second time? Here is a link that might be useful: Greer Gardens, Inc

I've had good luck starting mine just by spreading them out on top of a moistened Jiffy peat pellet and keeping them covered for humidity, under lights, and at 70 degrees F until they germinate. Might be good to start them as soon as possible so they don't dry out.

Maybe it is root-bound. Are roots growing through the drainage holes? I would place the pot in a large container or a tub filled with water. If it perks up, I would re-pot it in a much larger container or split it. 10 years old. It must be humongous. Also are you keeping it out of the sun? Good luck.