Going to try and post this here instead.

Both of my skele spawners have quit working.
Nothing was changed for a year almost.

The mobs are spawned....go up the water elevator and then simply despawn at the top and never fall down to be farmed.

Any ideas as to what has changed on the server or how I can get them going again?

Thanks!

My experience is similar.   Shortly after the latest minecraft update, my zombie grinder didn't work like before.  I had a 20+ block elevator where they would rise and then drop to the kill zone.  When the zombies approached the top they would all disappear.  When i went to the top to inspect what was going on, they stopped disappearing and the grinder worked as before.  I think something may have changed in the latest minecraft update that affected the distance you could be from spawned mobs.  At any rate, i "fixed" my grinder by shortening the height of the elevator.  I believe the 16 to 20 block distance others have mentioned holds merit.  Although it's not as fun as before and the zombies take more hits before dying, there is a work around.

That's my two cents!

Max