HARRY,
We have sold around 4500 custom rigged Ospreys since this past October and have spent countless hours experimenting with them. We are able to get about 95% to run straight at any speed.
The ones that don't typically have an off-center nose hole and there is nothing you can do with those. You need to check that when you buy them.
I won't go into the whole process but the key things are the alignment of the hooks to the body, the belly weight and using lead nail weights to offset the tilting of the bait.
Both hooks need to be inserted so they are in line with the bait and each other. The rear hook can cause a kink in the back of the bait if its not pushed in straight.
I like to cut the hole for the belly weight at a forward angle underneath the line tube and dead center. It helps to have the added weight towards the head of these baits as they normally want to plane upwards. We use a 5/32 oz. Mojo weight for both the 7 and 9 inch.
We then test the bait in the pool. If the bait wants to roll up on one side, we insert one nail weight about 1/3 up from the belly and just behind the eye. Push it straight in towards the tail at a slightly inward angle. If the bait still rolls, put another one in about 1/4" higher on the body. Sometimes it may take 3 or 4 of these and then the bait will roll up slightly on the other side. When this happens, back out the last weight you put in and cut off about 1/4 inch at a time until the bait runs true. We use the 3/64 oz. on the 7" and the 3/32 oz. on the 9".

Hope this helps. Jeff T.