You know you have mites, but did you give that plant a high dose of fert........
Its kinda tricky in the winter, every time I fert. I get some burn marks like that..... ok here's what I would do... Repot, while repoting check for root rot ( cutt rot off)...cut main plant down to 8" leave pup alone..........do not water atleast a week after potting, let dry out... get a stick push in the ground let it in to see if soil is dry.....(stick trick) I barely water my saim ruby in the winter and the cure for spidermites (there is no cure!!!) 1 bucket of water a 1 sponge and a little dish soap, wipe the leaves off........... from one in your area..... now in my basement I have not seen a real problem with mites..... Anywhere I get dust in the house (furnace) you will find these little guys......
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