LEM
Once airborne, the DDPG is no longer relevant. The QRH is the controlling document.
First, limit airspeed to 230kts. If you have roll, it'll be a Flaps 15 landing. End of story. However, if there is no roll, then you can recycle the flaps to see if it will stow. If it does, great - no further limitation. If it doesn't, you have to see how many have stayed out. If it's just one, then you are limited to 300kts (.65) and a Flaps 15 landing. But if it's more than one, then you are limited to 230kts and a Flaps 15 landing.
In your scenario, it depends if you had roll or not. When there is only one light that won't go out, with no roll, then you are limited to 300kts (.65) and must plan a Flaps 15 landing.