How to fix this? (woodwork)

[Juggular]

As I was taking this photo today, I noticed that I didn't quite fix the staple marks on the stairs.  

There used to be late 80's PINK carpet on the stairs.  After 40 years, it was more like porky SPAM color...  And the house had a leaky roof.  The previous owner had a blue tarp on the roof for several years.  With all the moisture, the staple marks have browned. 

On the inside, where feet can't really touch, I could glue a thin strip of actual wood carving (they are like paper, but real wood).  The exposed lip-part has to be stepped on.  So I drilled them, and stuck in toothpicks, and roughly sanded the area.  Tiny spots were removed that way, but bigger spots still show. 

These browned 1cm deep. Sanding won't work.  Paint or putties would rub away, too.  Is there some carpentry trick to remove these ugly staple marks?  (I did cut up a chopstick to peg holes after removing screws on a door. That seems like an overkill here)  Vertical areas were simply wallpapered.  But wife wants exposed-wood on top, and replacing the steps could cost more than a few RC cars...  I'm not keeping any hopes up... Any carpenters in TC?  

[djmcnz]

Saw/wood dust with glue. Even better if you can get to the back of the stairs so you can collect dust from the same timber.

This is how cabinet makers do such touch-ups.

https://www.doityourself.com/stry/how-to-make-wood-filler-with-sawdust

https://www.thespruce.com/homemade-wood-filler-1822282

 

[Kingfisher]

What the previous post says, or sand passed the discoloration along with the rest of the finish and restain them.

 

 

[geniusanthony]

i have soaked stained hardwood with hydroden peroxide. I place a dampened towel over the spot, sealed with plastic and duct tape, leave it for a day recheck, re-wet, killing the organic compounds is the trick.

[Juggular]

Wow, this is why humans cooperate!  er... I'm a human too, and I'm receiving the help, not cooperating, but you know what I mean...

Saw dust filler from the same type sounds good, I should try peroxide too.  I don't think there is any living thing since the house is dry, but it will kill and bleach.  Now I've got two things to try.  Thank you, gentlemen.