This 1969 valve has a 1.5 inch diameter nylon cartridge that I am having difficulty removing. I was able to remove the handle, outer half of the spherical seat, and stem spherical toggle. The rest of the cartridge has nothing to grab onto but I can rotate it but will not slide out. Is it being held by O rings, require special puller?, is the cartridge removeable or must I put in new valve?Would appreciate any info on cartridge and availability.Thankx