Bootcamp Partition Not Bootable After El Capitan Upgrade

Hello,

I had this happen the last time I upgraded the OS to Yosemite. You'd think I would have learned-LOL!

Here's the deal:

I have a Windows 7 partition that is showing up under disk utility but it won't show up when I start the machine pressing the option key. Only the Macintosh HD and the eDrive for Techtool Pro 7 are there.

The last time I did this there were a set of command line instrucitons that work like a charm but I can't find them because I must not be using the right keywords.

Does anybody know how to do this or know where the instructions are?

I ran them and voila, restarted and there the partition was and it booted. It's not damaged. Just the MBR has been fooled again.

BTW, why does this keep happening? Do they really not have anybody who runs a dual machine any more? Why would any upgrade install change the MBR?

Just venting.

Thanks in advance for your help,

Jeff