Boss HM-2 Help/Tip needed

[MarkIII]

My Boss HM-2 MIJ has low or almost anything sound out when it is engaged. Turn up/down level pot doesn`t change anything , but i can hear the Eq blending and distortion blending , but the output is very low.

I have read some old posts in here about e few problems , but haven`t got any ideas for what it could be for this one.
And any tip for where to buy parts for the Boss pedal ( close to original parts )