Hi. I have had a Kentia Palm indoors for over a year now. It grew well initially, but over the past 6 months or so has slowly developed patchy brown and yellow leaves, which is progressively getting worse. I thought this was due to sun damage and so moved it to a spot with no direct sunlight. The leaves are now browning at a furious rate on some fronds, and is spreading to most others. I give it about a litre of water once a week. It is in a light but not direct sun position in a warm room (upstairs). See photos attached. Any suggestions welcomed.