Zenith Z25X31D Verticle Adjustment

To do this adjustment, you should enter the service mode option. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/
Service mode entry, adjust and exit procedure to many popular brand TVs are given.

Either an adjustment of the vertical height or Lin or a circuit problem in the vertical circuit.

Some sets have physical controls inside the set on the board or in a hidden menu via the remote.

The vertical position and height adjustment to your TV has been changed. with modern sets, there is no manual adjustment at its main board to make these right. In older sets, these adjustments were there on board itself.
If you want to change these parameters, you have to enter its service menu option window. It is a skilled job, even though a technician have no need to open it. An experienced tech; only can do this. So contact any of them for help.

It's not an adjustment.Chances are it's your vert. output i.c.or a surrounding component.Chip # is TDA8172.

picture horizontal in the tv

Probablemente tengas problemas en el circuito vertical o los capacitores adyacentes hay que checarlos.

Use your remote to reconfigure the picture. There may be a picture button on the remote that will switch the picture from 4:3, 16:9, Standard, Stretch, and so forth.

Is the picture overall too small by 1 in. on top and bottom? Or is it cut off by the lines?

If it's too small, look for an adjustment labeled Vertical Height. This may only be accessible internally, it's normally a service adjustment, not a user adjustment.

Your problem is a vertical deflection issue, either an adjustment or the vertical circuit requires repair by a technician. In the latter case, electrolytic capacitors are a likely cause.

Thats is not going to fix your problem. You have a bad vertical output IC and or a bad capacitor in the vertical drive or output circuit. Good Luck

there are a couple of coils that are for pincussion and width that get cold solder connections on them and sometimes will blow out the curcuit. Maybe its not to late to resolder them? Good luck