You probably know those drives are notorious for their unreliability and prone to fail without warning .I had two, a Kalok Octagon MFM/RLL and a JTS which is same company different name, both failed the JTS I still have it, some day I will try to repair the heads, the Kalok was recycled as most people probably did, so very slim chances, looking at the PCB the two resistors on top are around a regulator of some sorts perhaps you can reverse eng. the circuit if you google what that comoponent reference circuit is. the R19 seems to be between 100 and 1k, I'd put a 1k resistor and test it then lower it to 470 ohm etc. good luck!.

Thanks for the tip!
I took a closer look at the top corner and redrew the schematic. It’s a standard window comparator for 5V and 12V. Based on my calculations, I selected the following values: R2 = 1 kΩ, R6 = 12 kΩ.
Resistor R19 measured 1.3 kΩ, so I left it as is.
The most interesting finding: while performing the repairs, I checked all the resistors on the board and discovered that seven of them were either open-circuited or had an extremely high resistance (over 5 MΩ).
If anyone else happens to work on a hard drive like this, be sure to check the resistor values. I suspect this was caused by a combination of aging and the use of somewhat low-quality components.
In my case, the faulty resistors were R17, R49, R51, R55, R56, R62, and R82.
I spot-checked the capacitors, and they all turned out to be fine.