Well, it appears that the image is being compressed.
Can the moderators allow a larger attachment? I have it down to 256k
resolution is 3040 x 2107
File size does not appear to be the issue. For instance Lee's PDF is 1.39 MB.
Getting an image that is 3040 x 2107 pixels down to forum size, and still keep the detail read-able is going to be difficult. The font size of the text looks too small for one thing. You can not "zoom-in" on the embedded images or the larger pop-up images.
The embedded image is about 589 pixels width, obviously it must be that width in order to be embedded within the content box. When you click on the embedded image another larger image pops-up … but there are limits to the size of that pop-up image too … the software will reduce the size of the image to fit within whatever the limits are. The pop-up of the schematic's image is 1000 pixels wide right now. 1000 pixels width is most likely the width limit. I do not have the option to adjust that limit however.
The PDF that Lee posted looks good, and you can zoom-in to see detail.
I shared some ideas with Lee via PM on how to best resize the PNG or JPEG files, but I suspect you're not going to be able to read the text, and the lines will be so close together that it will be hard to follow them.