If the sliding covers are not the issue, It sound like the feed screw nuts might be loose. Move the saddle (Y) out towards you as far as you can go and lock the lock screw or place a wood block behind it and the column and remove the 4 aleen cap screws holding the feed screw bracket to the front of the the knee. No need to remove handle or dial..so leave that alone.
With the 4 bolts removed crank the handle and the feed screw unit will come out toward you. When it is out, look in the hole and check the flat head bolt (aprx) 7/8 dia. head that holds the 2 brass nuts in the bracket. I suspect the screw is loose. It has 2 brass nuts in the bracket hole and they work as a backlash eliminator. If that's OK I check the feed shaft dial and see if it and the bearings retainer ring is tight (the one you just puled out) sometimes they get loose and lets the feed dial drag on the bracket.
One more thing would be the gib, bit usually when they are loose the bind up when feeding out as they go deeper into the taper. The gib screw and knotch in the gib may be loose allowing the gib to move up and down and and bind up kitty wom-puss. One more thing when you re-install the feed screw be careful not to cross thread the screw when starting into the brass nut. If it has roll pins in it, you may want to remove them or tp them back so only a little is exposed on the inside of the bracket. Trying to get them aligned when they are sticking out all the way might end them when screw the screw back in. Good luck and if you need more info please PM me. I am a rebuilder and have rebuild hundreds of Bridgeport's over the years. Good hunting :-)