Korps, take all the weights out and balance near the fuse.
If I were you I would strongly consider putting something like an OS .55 or and evolution .52 in the nose up front, you will have a much better flying plane with plenty of power to spare.
See if you can borrow or buy a CG tool like the Great Planes one. I used one and the results were very different to fingers every time. If you can't get one tape 2 toothpicks to the underside of the wing on the CG and put your fingers on those. Balance is important. Do it yourself, it doesn't sound like whoever is helping you is putting enough effort in if they left the weights in with the bigger engine. That could easily have destroyed your aircraft.