I don't do Schutzhund style tracking, but I have earned TD's on a half dozen dogs, and gone on to earn TDX's on three of t hem. So, my advice is going to come from the perspective of a less precise style of tracking, but I'm by no means so permissive that I allow my dogs to cut corners by more than a few feet, or wander all over the place, or anything like that.
First of all, no matter what anyone tells you, and no matter how certain they seem, no one, including me, really knows what scent does. But, since what you've been doing for some time isn't working, try something else. Contrary to all the advice you are getting here and from your trainer, I'm going to suggest that maybe the problem is that there is too much scent on the track. Imagine that you walk blindfolded into grandma's house on Thanksgiving afternoon. Yummm! The scent of roasting turkey is everywhere. Now, imagine trying to locate exactly where that scent is coming from. It's probably going to be pretty darned hard, because you are just in the middle of a huge scent cloud, and so it's very hard to pinpoint exactly where the scent is coming from. I know lots of people who use scent in a bottle, scruff tracks, use scent pads, etc, and they are very successful, so I don't want to say that those techniques and tools are of no value, but I also think that often we approach tracking problems from a very anthropomorphic point of view; we assume that since our limitation is the inability to detect the scent, that must be the dog's problem as well. But I've frequently found that dogs do at least as well, or often better, in the beginning stages is we try to avoid overwhelming them with scent.
Here's what I would do, and I honestly can't "promise" that it will work. It's just what I would try. Forget the scent pads. Lay a piece of food about every third or fourth step or so. Let the track age about 15 minutes to a half hour so that a lot of the extraneous body scent has hopefully drifted away. Keep your dog on a short lead - 6 ft or less, and don't let him wander more than that lead length off the track, but don't be too concerned if he does a little quartering, and doesn't sniff every single foot print. If he skips food, don't make him come back for it, but if he overshoots the food by a couple feet and comes back, allow him to do that. I would put a big jackpot at the end. You can put the jackpot in a container so that he can't smell it as much to help prevent him from just air-scenting his way to the article. Putting the food in a container also teaches him that he has to show the partner with the opposable thumbs where the article is if he wants to get his reward. I know you want him to focus on the "journey, not the destination" ;-), but for now the objective is just for him to love finding his article, and to realize that staying close to the track is how he gets the article. Once he is doing straight track of 50 or 60 yds reliably without a lot of zig zagging, I would start spreading out the food, until you may only have one or two food drops along the way. You will probably find that he stays more faithful to the track once there isn't the overwhelming odor of food permeating everything around the track. I realize you are probably cringing at this because I'm really not suggesting you do anything specific to encourage a deep nose. But my experience is that as the dog gains experience, the track gets longer, and the age of the track increases, the dog automatically has to work harder and most dogs become more faithful to the track and develop deeper noses on their own, provided you don't let them do a lot of random wandering and searching, but maintain a short lead. Again, think about yourself trying to follow a track of tiny droplets of perfume across your living room carpet, versus trying to follow that same track if there were bottles and bottles of perfume dumped on the carpet. In the latter case the odor would be so intense and so spread out that it would be difficult to figure out exactly where the odor was originating from.
If you don't already have it, I recommend Enthusiastic Tracking by William (Sil) Sanders. Sil is an AKC tracker, but I've seen his Westies track, and believe me, they are faithful to the track, and very very methodical. Boringly, frustratingly methodical if it is cold and raining and you are waiting for them to finish a track so you can go inside and warm up ;-). I don't follow Sil's protocol precisely, but for a new tracker, I don't think you can go too far wrong with his lesson plans.
Finally, is there a particular reason why you especially have to develop a ScH style of tracking? Are you going for a ScH title? I'm not criticizing their program - I've seen some absolutely fantastic ScH style trackers. But, I don't think it's a style that is suited to all dogs, and hate to see people with perfectly excellent trackers give up on the sport just because their dog doesn't fit one specific style of tracking.