Question
I had sympodial orchids with the growing of a new growth, that started thriving but when the growth was growing well, stopped growing and the new growth got smaller than the other bulbs.
why happen this thing
how can I encourage the growing of a new growth with healthy roots until it get bigger or at the same size of the other bulbs?
how can I encourage the growing of a new growth with more less healthy roots until it get bigger or at the same size of the other bulb?
how can I encourage the growing of a new growth with rotted roots or with no roots until it get bigger or at the same size of the other bulbs?

Answer
Jorge, Most problems with orchids are in the root zone or with timing.  As I explained with your dendrobiums, plants should be watered and fed only during active growth-- and not when at rest.  Same for repotting. Many orchids have natural growth cycles and will respond to watering, feeding, and repotting, only when in active growth. When this is done outside of their natural rhythm, they can begin new growth out of their natural cycle and the new growth will be smaller and smaller and/or root problems can set in.