As an ex british gas engineer i would advise the same as i do know the parts are obsolete for a reason , they are at the end of there life and if u can find a flue if then another part goes wrong possibly over heat or modureg your in the same boat pull it out and put a decent condensing boiler Worcseter ri range or gloworm hxi or the like , just an opinion jim .
Jim Hough
March 2009