Might be worth trying to dip just the head into ~100-110 degree water for 30 seconds or so. Get just the head really nice and hot to make a better target for him. (Or blow dry that spot particularly if he refuses wet rats)
Or, maybe change how you dangle the rat so he has "no choice" but to grab it head on? I.e. hold it by the scruff with tongs and present it face-first as if walking toward him & froze in front of hik. If the head is hottest & the most prominent target, he might have better odds hitting the right place & eating more reliably.
I'd still want to know his weight & the weight of the feeders personally. Not now if he is digesting, but sometime since things sound a bit off to me. Small rats typically weigh 50-80g, some variations of the upper and lower end depending on the seller. And most 6-7 month old BPs I've seen are not really big enough for that size feeder. Some can be of course, but most of mine I've gotten at 3-4 months old were sub-200g and did not get over 400g (weighed after a poop) by 6 months, males especially. 10% feeder for a 400g BP is around 40g.
In the meantime, maybe a picture of him? With something easy to judge as a scale?
If yours isn't actually up to weight for small rats and your small rats are the 50-80g range, the feeders may be a bit larger than he's comfortable with eating and he is only noticing it once wrapped when he doesn't grab the head. Might not be the case, but without knowing the weights it is hard to say.
With right sized feeders and an enthusiastic strike, it is very unusual for him to be dropping the feeder. This coming from someone with a spider that does display some wobble, particularly around feeding, and has more issues hitting the rat than reorienting to eat it after.
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