Advice on how to best to play

[Journey55]

I'm having a little trouble playing the part in Blood Brothers (I guess the interlude) where he plays:
|-----9---9---|
|--------------|
|-7-7---7-----|
|--------------|

And moves that around. So I'm playing the 7 with my thumb and 9 with my index finger but after a while my thumb starts tensing up....any alternative ways to play it/suggests to help?

[Duckwater]

I suggest a 2 finger technique (index and middle) for any Iron Maiden song

[Journey55]

I normally do but I saw that he used his thumb and index/middle fingers for this song so I figured I'd take a shot that way

[sammyp]

well i don't know the song so if it's slap bass ...i would go thumb on the A string and middle on the G string .....

if it's not slap i would lead with my middle on the 1st 7th fret then index so that my middle is ready to go to the octave 9th fret

then index 7th fret and middle 9th fret again

that's how i approach the Immigrant Song riff too! lead with the middle finger ...

[F Clef Groovist]

If your thumb's tired try moving your right arm angle down to more of a 45ish degree, kinda like classical guitar, if you're not already doing that, and use a little bit of arm on the thumb notes. Make sure you don't use too much arm preassure, or tence up. You have more arm strength thatn finger strength making it easy to get a harsh sound. Keep your thumb and middle finger a little wider than the 3 string spacing. Still use a little bit of little finger motion (more middle than thumb), and just treat it kinda like a guitar picking pattern v v^ v^ except this is just a very slight arm motion unlike guitar chords and you're wearing your guitar really low and have to play with almost all arm.