Welding: Recovering from a poor joint.

I have been given a patched landing gear. The weld looked like
bubblegum had been stuck to it and there were little pits where any
metal that had flowed, didn't flow around that impurity. I asked my
A&P if the embedded impurities hadn't been an issue, could I simply
remelt the joint and cause it to flow into the base metal? He
replied because there was so much 'joint' there, heating it up to
molten could cause more harm. He recommended I grind as much of the
old weld off as possible.

I have an angle grinder and a grinder wheel for it. I can get to the
weld, but even if I jig the work, it's going to be awkward to grind
with this tool.

Anyone have any suggestions how this might be made to go smoother? -
MikeH