Yes, if the water has slowed down to a trickle, that means the water filters need to be replaced. The filters are no longer able to filter the water - they are full of sediment and other contaminants.
Flotec is no longer selling filters but we do have a cross-reference sheet. The cross-reference information I have directs me to the P-250A water filter set.
Pentek P-250A replacement filters and Pentek P250A under sink water filters
There are 2 filters in this set and each filter is 9.75" L x 2.4" W. Please verify these dimensions will work in your current system. These filters should be replaced every 6 months. Even if the flow rate does not decrease, the filters won't be able to reduce some of the contaminants any longer.
Thank you,
WaterFilters.NET