The END key only works for tables that have DMD's.
I always download an operator's manual from IPDB.org for the pre-DMD tables to figure out how to adjust volumes.
There are many tables that just had a volume knob inside of the cabinet.
For these tables, you can use the Tilde key method for raising the volume.

First you need the PinMAME window to be accessible with your mouse.
There are 2 ways of accomplishing this.
1)
You can go into your VpinMAME folder and run PinMAME32.exe.
Double click the rom to run it.
Once it is running, left click on the PinMAME window with mouse and hit the Tilde key.
This will bring up volume options, that can be toggled with the left and right arrow keys.
Press down arrow key for more volume options.
When you have finished making your adjustments, hit the Tilde key.
Now close PinMAME32 window.
Your settings should be good on next run of table.
2)
You can get to the PinMAME window by going in table script and on LINE 47 you will see this...
.Hidden = 1
Change this to...
.Hidden = 0
Now the PinMAME window will show when table is running.
Left click the PinMAME window with mouse and hit the Tilde key.
Use right and left arrow keys to toggle volume adjustment.
Hit down arrow key for other volume adjustments.
When you have finished with your adjustments, hit the Tilde key and restart table.
Should be good to go.