Having to pull the converter forward to the plate is absolutely normal, but what I would do is pull the valve body and air test the clutches and bands.
Of course paying attention to the pan contents and fluid condition.
You might just have a valve body problem, or it could be a massive internal fluid leak.
The air test would tell you, but it would be a really good idea to get a gauge on it and test the pressures before you tear into it.
