ORIGINAL: BMatthews
I'm not sure I understand what you did with that weight. But it sounds like you flew the model the first time without checking the balance at all and then added these weights and moved the parts in order to move the balance location to where it is supposed to be according to the instructions. If so then yes, it's quite normal to have to do so. Variations in wood density, engine and radio equipment choices and a host of other variables make it impossible for an ARF maker to ensure that the balance point comes out spot on for you. Setting the balance point is something you need to do with ANY new model.
Basically in a nut shell I did a quick balance (close), then changed the muffler added the cowl and flew it without rechecking it. Both times it flew badly. I had to add 3oz to the end of the tail to get it to balance right, .5 oz to l wing tip. Would this amount of unbalance make it fly like a POS on my previous flights? or should I check elsewhere?