random character generator CMD doesn't work

can anyone help me pls.. I've made a random character generator in CMD but it doesn't work, how it does? Here's the code:

@echo off
:1
SET /a LOOPCOUNT+=1
SET /a _ran=(%RANDOM%*94/32768)+1 
SET _crs=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*()~`-_=+[]\{}|;':',./<>?
SET %LOOPCOUNT%=%%_crs%:~%_ran%,5%
IF %LOOPCOUNT%==8 goto ECHO
goto 1
:ECHO
%1%%2%%3%%4%%5%%6%%7%%8%
pause