Case 580se shuttle/torque converter

I have a 1985 case 580se backhoe that is sluggish in fwd, rev works ok till fluid gets warm then almost no travel. I am planning on rebuilding the shuttle. the question I have is about the torque converter. I would rather not replace it if not necessary so is there any way to separately test the torque converter? I understand doing a stall test is the correct way to test the converter but if the shuttle is slipping wouldn't that give an inaccurate gauge on the condition of the converter?...

Case 580se shuttle/torque converter

Case 580se shuttle/torque converter