I'm with Big... No wander at all, at any speed. Straight as an arrow. I run a 225hp Yamaha two stroke outboard. It's light weight at 411 pounds. Also it is mounted about two inches above the typical transom lip. No wander at any trim level. I also have some additional weight forward due to a large fiberglass and aluminum hardtop

In Big John's case, I imagine the down-turned trim tabs offer some tracking assistance.

Handful, Looks like someone stole your tabs;).

Nonetheless, I think the absence of some pressure in the steering pump will prove to be the primary culprit of your Sceptre's sashaying issues.

My wife says... I can't dance, but my boat sure can!

My Bravo doesn't have a torque tab, just a flat anode. Alphas could be different, I don't know.

I don't know either,but my Alpha came with one,and as mentioned I removed it because it wouldn't clear the larger prop.
I don't notice any difference in steering without it.
From what my mechanic says,Mercruiser also has a lower profile anode for the Alpha drive that can be used in place of the finned version when you're running a large diameter prop.

In my case it's all freshwater,and I've since gone to launching and loading daily instead of a slip,so I'm not overly concerned about electrolysis.

Mine is better since I put hydraulic steering on it over the stock cable. But it is still all over the place when I idle back into the dock. Anything above a dead idle and it is very manageable with slight correction. But it is very easy to oversteer it.