I do recommend buying extra bearings before disassembly. They're cheap and easy to get. A non-magnetic tweezer will also be instrumental.
Any 1.5mm bearings will work. It is best if you use steel bearings and not ceramic, as that is what is recommended by Shirogorov. When it comes to bearings, the roundness is valued by a grade number. The lower the grade the higher the tolerances and more round the bearings. The lowest I could find at a reasonable price is grade 10.
(
https://insights.globalspec.com/article/12349/how-are-bearing-balls-made)
I bought extra bearings off of Amazon: (1.5mm 500pcs AISI 440C Stainless Steel Bearing Balls Grade 10 (AISI440C)). They don't necessarily need to be made of 440C.