It may be a bit risky, but from the description it's pretty straightforward: Don't look for the three bytes, look for just the first byte. Once you find that, check the next two bytes to look for a match.

The risky point is that you may get false positives. If those three bytes happen to occur as part of something else, and are not what you are looking for, the replacement could create a mess.

With that caveat, the solution is just to loop through each byte in the array looking for one that is 20. That would just be:
Code:
For x = 0 to bytes.Count-3 'No point in checking the last two bytes.
 If bytes(x) = &H20  Then
  if bytes(x+1) = &HBB AndAlso bytres(x+2) = &HBD Then
   'It was found at position X, so save X somewhere and keep on going.
  End If
 End If
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