Live or F/T. Very important when you are talking about food issues.

Also, does the snake grab it and constrict it, then release? If so, I find the following very useful....

I find that spiders and womas (particularly ones with really bad wobbles) have problems finding the head. The best way to get them through that is offer the snake the head of the mouse (if F/T). Instead of dangling the rat by the tail, use tongs and grab the F/T rat by the scruff and offer the rat on the floor of the enclosure (not in the air). This way he will have the opportunity to grab the head and not have to release to locate the head.

If he is fed on live, it may be a totally different story. Most snakes, when fed live, will automatically target the head. Sometimes they miss but in my personal experience, most snakes rarely miss and your snake should have no problem in such case.

How long has it been since he last ate and when did you get him? I have seen some snake just automatically eat every two weeks as their own personal schedule. I find this quite often in males. Females tend to be little piggies. As long as he is eating for you twice a month (if he is young) you should not be too worried. Sub adults can eat once a month and still gain weight.

It really would not surprise me if the issue is in fact the locating the head problem. Snakes will quickly lose interest if they have this issue.