Passed by Lor 5 Toa Payoh Food Centre, and recalled that there is a Song Kee fishball noodle stall here which I haven't tried so far.
Stall name: Song Kee Kway Teow Noodle Soup
Address: 75 Lor 5 Toa Payoh, stall #01-20, Singapore 310075
Nearest MRT: 10 minutes walk from Toa Payoh and Braddell station
Hours: 10:30am - 10:30pm (Weds off)