Hi Hippy, here is my code according to your example:
symbol varA = w0
Do
For varA = 76 To 200
Servo b.4, varA
gosub buggymove
Next
For varA = 200 To 76 Step -1
Servo b.4, varA
gosub buggymove
next
Loop
pause 20
return
buggymove:
low B.0,B.1 'motor forward...