First, let me just say that using Windex scares me.

Second, whatever you use it is imperative that it completely dries before you insert a tape. If there is any left over moisture the tape will stick to the heads and ruin them.

Third, do not go up and down.

Lastly, you may find this useful: http://www.repairfaq.org/sam/vcrfaq.htm#vcrvhctech