Corning Ware stovetop pots take a little longer than Pyrex or other types of pots to start to perk, but once they come to a full perk, let it perk for 8 minutes, no more. Be careful what heat setting you use on the stove - the flame should initially cover only the bottom of the pot....don't let it creep up the side or it may begin to melt your handle. They make pretty good coffee. Make sure the pot does not boil over...if it has a snap on cover, rather than the screw on type of cover, the top can literally blow off the pot if the pressure builds up too high inside. It's quite a mess to clean. The screw on covers, where the basket screws into the cover, which then screws into the pot itself, is probably the better of the two setups. The snap on covers are found on the older Corning Ware pots. I have 5 pots, two electric, and have enjoyed using them for many, many years. They're all over 35 years old.
If the cover of the pot has a glass insert that is glued on, rather than one that screws into the cover, make sure the setting is tight. They tend to give out with age, heat, washing, etc. It's a fun toy to play with, but takes much longer to make coffe than your drip pots or electric percs do.