Cymbidium with brown leaf tips and not growing

[Synthesyst]

Hi all, been reading this forum trying to keep my orchid in good shape, but it doesn't seem to be working very well. I received it as a gift in August last year while it was flowering, and it seems to not be growing very well. I haven't inspected the roots thoroughly as I don't want to damage the plant accidentally, but the ones I can see seem to be rather brown and soft.

Just looking for what I should do to keep the plant healthy, I hope I still have time to save it.

Mainly concerned about the brown leaf tips, I snipped them just below the discolouration a while ago but it seems to have returned on most of the leaves. Additionally, the new sprouts(?) I have shooting up appear to be having a similar problem. The healthiest looking growth is also 'loose' which makes me fear that there isn't enough potting mix for the plant, or the bulbs/roots have issues.

I've attached pictures and some more information below. I'm new to houseplants and orchids in general so I'm not great with the terminology, but happy to answer questions or provide more photos.

Watering: about weekly, tap water which I try to keep room temp, let it drain out through nursery pot before placing back into decorative pot. Perhaps I am overwatering?

Light: near a north facing window currently.

Fertiliser: infrequently, probably once every 1-2 months, using a slow release fertiliser. I may have used too much of this in the past so I tried to flush a lot of it out.

Thankyou!