Maineiac1,
You have a few issues.
The first is that you have "customers" when you can't seem to grind a knife. Please don't take that as being mean. But it doesn't seem like you are ready for that. Get your basic skills up to speed before you go there. Having customers waiting for knives is enough pressure when you know what you are doing. Adding that kind of pressure at your stage is unnecessary and not allowing you to make the natural mistakes you need to learn and grow at this point in your development.
Now let's talk about your biggest problem. You may not want to hear it but I think you should put that jig aside for now. The jig is handicapping you. New makers may think that jigs are a shortcut to making professional quality knives. It's like a kid with a learners permit license driving a car with a blown alcohol motor because it'll get him there faster. Get you where faster? Jigs lock you into a position which makes it hard to adjust as you go. Learn the basic techniques of grinding by hand. Then when you have a good grasp of that and have consistent success you can go back to jigs to speed up processes of which you have a better understanding.
It's all about where you apply pressure, how much pressure, what angle the blade is to the belt and how fast the pull is. What it sounds like you are doing is digging in or angling the blade into the belt a bit at the plunge and then letting up on the pressure as you pull away from the plunge. Or maybe as you move away from the plunge you are adding more pressure along the cutting edge which will remove more material there and less at the spine, causing a dip at the spine.
Put the jig and work table aside for now. If you have variable speed, slow your grinder down a bit. The only "jig" I would recommend at this point is a carbide faced file guide placed where you want your plunge lines. Folks say to grind your weak side first so that you can match it on the other side where you feel you have better control. The fact is you should be grinding both sides equally as you go. 5 or 6 passes on one side then the other, back and forth. You don't want to grind one whole side then grind the other whole side. One reason is you don't want to put uneven stresses into the blade. Grinding back and forth from side to side keeps stresses more even and it allows you to see if problems are forming while you still have the room to make adjustments. When you get to the finishing stages, do your weak side first.
Stand in front of your grinder, feet shoulder width apart. keep your elbows at your sides. Stand close enough to the machine so you can see where you are grinding. Lock your elbows in place and use your legs to shuttle your upper body side to side when making your grinding passes. With the hand that is holding the tang, place your thumb on the ricasso (or on the file guide if you are using one). The support hand will rest the spine of the knife on the forefinger and the thumb will be on the blade. We will assume that you have marked your centerlines etc. As you approach the grinder angle the blade about 45˚ to the belt and carefully lay the edge into the belt and make a smooth pull out to the tip. Repeat as necessary. What you are doing is cutting the edge thickness down to your pre heat treated thickness. Leave roughly the thickness of a quarter. Work both sides until you are there. Now you are going to start changing the angle of your blade to the belt to raise that grind up the side of the blade. You are not taking any more material at the edge, only the sides. When you put blade to belt you are gently laying the bevel you have created down against the belt, feeling for when the bevel lays flat against the belt. As you begin your pass, the thumb on the tang will add a little pressure above what we'll call neutral. Neutral is the belt removing material evenly from the top of the grind to the bottom and side to side. If the bevel you have established is laying flat on the belt, this above neutral pressure will add force to the top edge of that bevel. This shouldn't be making a new bevel or facet. This should be widening the bevel you have already made. And this is how you will progress up the blade. Add pressure with your thumb where you want to remove material. If you have a grind that is dipping a bit in the middle, put your thumb at that location. Of course the blade is upside down so if you have a dip at the spine you are putting your thumb a little lower toward the spine. As you make a smooth light pull add a little pressure with the thumb as you pass the spot with the dip. You should see the dip start to rise. Repeat until the line is fairly even then make longer neutral pressure pulls to blend everything into a smooth and level line. Adding pressure is a subtle thing. You will develop a feel for it. As your grind gets higher you will want to start forming a radius where it blends into your flats or spine. This is a balancing act of time, distance and pressure. It is also aided by running the belt off the side of the platen 3/16" or so. Lay your blade gently on the belt, slide it over to the plunge line and add pressure on the spine side. At the same time you are adding pressure you are drawing the blade away from the plunge. That radius area is a very small distance so getting a feel for how much pressure and pull speed will take some trial and error. It helps a lot to scribe the lines of your intended grinds before you start. Leave yourself room to correct. Do not grind right up to your final lines. You will be cleaning up the blade and dialing in your final dimensions after heat treatment so leave a little meat on the bone.
When you get familiar with grinding mechanics you can speed up the process by hogging a lot of the material off using the contact wheel first then going back and flattening your bevels with the platen. At the point where all that feels natural then go get your jig. By then you will know how to read your grinds and will have the manual skills to fix any problems.
