How can I set '8' and '9' on a keyboard to slide along a discrete scale in the slider?

OS (e.g. Win10): OSX
PsychoPy version (e.g. 1.84.x): 2023.2.2
Standard Standalone? (y/n) If not then what?: y
**What are you trying to achieve?: Trying to make a slider from 0-7 where the ‘8’ key makes the value smaller and the ‘9’ key makes the value bigger.

**What did you try to make it work?: Tried adding keyboard responses using custom code to add +1 or -1 to the value when the keys were pressed. Tried using the outdated ratingscale option.

**What specifically went wrong when you tried that?: It will move back and forth on the scale but only jump between extreme ends of the scale, it won’t jump along the integer points even though I tried both granularity settings. 8 will just make it as small as possible and 9 will just make it as large as possible.