There is a description of this action in Len Reynolds "Dog Boats at War" (page 105) :
"The two boats made the long passage north to the Trondheim area during the dark hours, and at 07.25 [on 25 October 1943] they sighted two coasters off Bessaker, and immediately attacked with gunfire. one target, the Kylstraum, laden with 170 tons of cement, was crippled and driven ashore. A German report reveals that this attack drew the attention of a defensive patrol vessel from Trondheim to the scene, the ND16 (Moewe). She opened heavy fire, and as it was daylight, the MTBs retired under cover of a smoke screen. ND 16 raised the alarm, and from 08.15 onwards, aircraft were alerted to find the boats.
At 09.30, a flight of three fighters located and attacked, and were met by a fierce anti-aircraft barrage, which damaged one of the aircraft. Both boats were, however, hit and damaged, 688 having one engine put out of action and 669 losing her port 0.5in turret, each with some casualties. Ten minutes after the first attack another three fighters appeared to make a second pass.
688, the leading boat, was able to take avoiding action, despite which her 2-pdr pom-pom gun for'd was put out of action. 669, on the other hand, was badly holed on both sides and fire broke out in the for'd petrol tanks. The methyl-bromide automatic extinguishers could not function as the pipe had been fractured. Even worse, the mixture had escaped into the engine room. By this time, only one engine was still running, and the fire was out of hand, so 669 had to be abandoned. 688 took off her crew and fired into the stricken 669, which was last seen heeling over to port with smoke pouring from her. Fortunately, the fighters did not pursue 688, presumably being at the limit of their range, but she was shadowed by a BV138 and attacked at both 10.53 and then by a relief aircraft at 16.00, each time unsuccessfully. 688 got back to Lerwick early next morning."
Len Reynolds says that "the detail of operations by the 30th/54th MTB Flotilla" was mainly drawn from a report "compiled in 1988 for the author by Vice-Admiral H B Gundersen" who had himself served in the two Norwegian MTB Flotillas.
669 was part of the 58th Flotilla.
Hope this helps.