Knauf,
Your suggestion was an excellent one. I'v seen and used that technique and it works wonders with dogs that were having some motivational problems or were learning to search or respond in a new or uncomfortable area. I would only add the you have to be careful how much you talk to the dog while he is responding. Too much talking will change the dogs focus from the drug aid to the handler. Initially it would be okay but immediately decrease your encouragement while the dog is responding. The praise and encouragement ideally comes after the response has been made. Stimulus=Response=Reward. Too much talking all the time, soon will teach the dog to expect your encouragement which becomes Stimulus=Partial response=Encouragement=more response=reward...
Well you see where I'm going with this. I've seen good dogs that will find odor, scratch once and look at the handler for re-enforcement. I've seen excellent dogs that will totally focus on odor and respond with no regard to where the handler is and what he is doing. That's what we're training for.

Howard,
Thanks for added suggestions - I have used the digging theory, using the sand pile - but not as steady training - when I have had a dog with hunting and retreiving, but a weak scratch. I start there.

Use to do the boxes ALOT - quit doing it with my first dog, after the first time I went to do UPS packages. Instance attacking of the packages.
But it is a good way to assist in training.

Stay safe

Kevin,
Thank you. While I completely understand your logic I, fortunately, have been lucky enough to be involved with working dogs that have hunt drive to spare. Thus far I havent experienced what you have explained. The dogs I work with pretty much ignore, or arent adversly affected by the handlers' urgings while they are digging for their toy. Mark was saying that he is looking for a way to reinforce an older dogs' alert, or start out a new dog. Sounds like he has tried everything we have suggested so far, so I expect he is experienced. I agree that your point on stimulus-response-reward is something to think about in a new dog, or a dog with low hunt drive but, experienced dogs with high drive who just need to polish up an alert should thrive on the additional attention and respond accordingly.