Kenmore side by side icemaker bin on door, 6mths old, water is only filling part of the ice maker and those cubes are not very large, also changed water filter in Nov and red light is on again to change the filter. The Water on the door comes out very slowly but it always has since I purchased and the ice was great until a few weeks ago.

Concur with the water valve solenoid; have had this experience several times with two way and even three way valves. Pull the unit and remove the mixing solenoid after the water is shut off. Sometimes a simple good cleaning and reassembly can make a difference but a replacement is the best answer. Your water dispersion is timed by the solenoid to fill the icemaker. Ergo, the water being dispensed at both ice AND drinking should flow at 1 ounce per second, optimally. The filter issue could indicate the presence of hard water debris already in the system and you'll need to trace that all the way back to the plumbing valve. If it's a needle tap, remove it and plumb in a good valve, I hate those things.

Would suggest changing the water valve, if you live in an area with hard water you might also want to install a filter behind the fridge as the valve is not protected by the filter on the unit.
Could be under one year warranty of unit, ask where you bought it.
The schematic is down in the front grill with information on the ice maker, emitter-receiver boards, etc.......There is a adjustment screw on icemaker to change cube size, but not unless you pull icemaker to pop cover. Its a time fill, testing the cycle is complicated, best to try a new water valve.