How do you tension the Y Axis belt?

My SV04 has been working perfectly since I purchased it a couple of months ago, many successful prints. Today, the Y Axis belt started slipping on the Y stepper motor. My reaction was to adjust the Y Axis tension, but I cannot figure out how to do it. There is no obvious adjustment and searching the manual and searching the internet have not turned up instruction on how to tension the Y Axis belt. If anyone knows the secret, please share. Otherwise the printer as is is useless.

Followup - from looking at pictures of the SV04 on the web, I just realized that there is supposed to be a Y axis tension adjustment knob on the Y axis belt pulley housing at the front of the machine. On my unit, that knob is missing, and closer inspection indicates it must at one point have been knocked of and the remaining screw is flush with the housing surface. I am guessing I will need to contact Sovol on how to replace the Y-Axis tension adjustment knob unless there are other suggestions.

Belt tensioning is described here: SV04 Operation instruction.pdf, page 8
That missing Y-axis knob is just a M4 knurled nut.

I found the nut and was able to push the tensioner screw out enough to re-thread it, so problem solved