Spindle RPM not matching program

Hoping I can get some help with spindle RPM. Purchased a G0704 conversion from Midwest Machine several years ago. The computer controlling it had a hard drive crash and since have had it repaired. I did have the Mach3 backed up and have re-installed it. I have compared some notes from documented motor tuning and other areas that I had done some "tuning" and everything appears to be back to normal. With the exception of my spindle control. It turns on in the program like it is supposed to but the spindle was running about 3 times the programmed RPM. Program called for 1000 rpm and after running a hand tach on it I discovered it was running about 3200 rpm.
I dug through the Mach manual about spindle speed control and I can't decipher and make it work.
The motor is the "stock" G0704 1 hp 110 motor with what appears to be 4300 rpm. The Spindle Pulley set up in Pulley Config was set up with Min 0 Max 1000 Ratio 3.9, a Min 0 Max 4000 Ratio 1, a Min 0 Max 8000 Ratio 1. Which doesn't "add up" to me. The drive is running through the stock gearing set up. Motor 25T, 37T driving the jack shaft, hi-low @ 42/62T driving spindle 60/70T. I have always run in hi gear with no trouble. I normally don't program higher than 2500 rpm. The spindle seems to complain at anything much faster than that with the gear set up.
I did some experimenting with the multiple Pulley Configs and each create a somewhat accurate picture depending on different RPM ranges.
I never put a hand tach on it before this so I guess I don't know where my rpm really was but I am sure it wasn't this far off.
Does anyone have an idea where I should be looking. The motor has a single magnet and a pick up on it. I haven't noted what board is in the box. I have seen that a few people have purchased these Midwest Machine conversions and I can't find them anymore so I was hoping for some experienced guidance. Thanks for any input.

Play with pulley settings for a bit.
Min 0, max 1000, ratio 3.9,
would mean that at 1000rpm it would be going actual of 3900rpm (wouldn't it?).

I've never had it perfect. I've 3000rpm max machine.
At min 100rpm the spindle went 150.
At max 3000rpm it went around 3300rpm.
You get it kind of centered on a linear graph of 2 lines. So for me it was something like: 100rpm =75 & 3000rpm =3100 in the end.

Not used Mach for a little while. Can take a little fiddling of pulleys and voltage %.

Thank you for the input. I was digging in the Config last night after I posted and found a few more pulley set ups. I ran them and tested with my tach. Based on your input and the idea that I never put the tach on it before this, I probably never had my RPM "perfect" from the beginning. Thanks again.

In PoLabs we also make it, and upgrade our CNC lathe with new spindle motor and configure it correct and we are very happy with upgrade.
You can check our blog posts about upgrade:
https://blog.poscope.com/cnc-lathe-spindle-motor/
https://blog.poscope.com/cnc-lathe-spindle-motor-2/
I hope this can help.
Best regards