Poor recording at start of tape

Hello. This kind of sounds like the loading deck is a few teeth out of time. In other words the tape is not fully dropping down. When the drives start pulling at it the first few minutes of playing it probably seats down a little further and a little further until it finally bottoms out and seats correctly. This I have seen before. The timing issue can result from pushing a tape in a little hard at times instead of letting the loader pull it in itself after it makes its first switch. At some point the loading deck went out a tooth or two and has remained that way ever since. Putting one of these loading decks back in "time" provided there is not any damage to the loading gears should be handled by someone experienced with this. If your familiar with gearing it would simply be a matter of marking the gears when you "trick it" to load a tape. The metal tape retainer should hit bottom when it drops in. When you start your re-timing process you only go one tooth at a time until you finally get it to hit bottom. You should not go a tooth more because you may cause damage to the main gear or one of the others. Good-luck and hope this helps.