Modifying Einhell BT-GW-150 H8513 PCB for Better Speed Control

Hello
I need advice on how to modify the H8513 plate of the Einhell BT-GW150 migomat feeder. As the wire feeder was dead in my blink, I needed to replace it with a new one. After the replacement, it turned out that the new wire feeds too quickly and despite the speed control on the potentiometer, it is difficult to weld only in the lower range. Of course, the feeder is some standard 12V plastic, but the motor is kind of a bit bigger. The control board is standard as in the BT-GW-190 with the symbol H8513 and it is certainly functional, because I checked it on another twin Powermat3 and the operation is completely similar. I am asking for advice on what and how to convert on the PCB (which resistors should be replaced) in order to obtain a larger adjustment range (of course with an indication of low speed, which may even be close to zero).
I will be grateful for your help.

You bought a 12V feeder instead of 24V - and here's the whole problem. The thyristor regulator will be difficult to adapt to work with such a large delay angle. (he can "break off the fire").

Well, it can be like that, but it was already equipped with 12V and it worked somehow. In addition, somewhere on the forum I read the theory that the drive should be for the same voltage as the PCB, and mine is supposed to be 12V. Today I "played" for a while and checked the feeding speed of the feeders. It turned out that the old feeder feeds about 30-35% slower than the new one. Perhaps it would be enough for the correct operation of the migomat. However, the feeder is already there and it would be the cheapest to convert the plate (if it is relatively easy).

Add 1k? in series with the potentiometer and check.
Depending on which end you turn it on, you will get a shift of the RPM range up or down.

I thought about a solution like this, but I couldn't do it yesterday. But I wanted to replace the potentiometer with another to maintain the control characteristics, and if I add resistance in series, I do not know how it will react. Of course, I will try to do this - it may just work correctly. Before that, I will try to change the R10 value to a smaller one (I will add a second 10k? to it, because it's the easiest way without removing the plate) and I'll see.
But yesterday I connected another feeder (probably from Kabit na 24V, at least such a shallow one) and it behaved very much like the old one, i.e. a bit slower. And does anyone know at what speeds such a wire in a migomat should run at all?

The wire speed of the standard Bester 1800 turbo feeder is from 0 to 18 m / min.

Hello after the break.
I did not manage to do much on the subject, because the feeder motor must actually be 24V and the lower revs are not necessarily satisfactory. As for the changes in the values of the elements on the controller board, only the replacement of R14 from 430 ? to 1.5 k? introduces some improvement in the lower range. Engine operation is still uneven. The engine works like "jerks". In addition, what I thought when analyzing the diagram, the regulation is not in the full range of the potentiometer. In extreme it is slow, then as if it slows down a little more and only then accelerates to high speed. So for now "kiszka". The next step is to control the circuit from an external transformer, maybe it will be better.

Or build a layout like the US-25 straight on Ne555.
link

Hello
As I wrote it and did it, that is, I powered the circuit from an external transformer and it's ok. Maybe it's an easy way, but it's effective. I consider the topic closed.