02 Toyota Solara Autotransmission woes 2.4 L

Some months ago my wife's car experienced transmission failure. No forward or reverse, no traction. I had the car towed to a shop and they informed me that the filter was stopped up and they replaced the transmission filter, the fluid, and wishing me well, they advised me that the malfunction would probably continue. Twice more the filter was clogged and I replaced it and the fluid myself. Each time I noted the increasing amounts of metal slivers on the magnets affixed to the pan.

Now the units suffers a pronounced loss of torque when shifting from 1st to 2nd gear. Loss of drive, a racing of the engine. When the throttle is then released the unit shifts on into 2nd and all is well. No such casualty ensues when shifting from 2nd back into 1st. The casualty is more pronounced until I again, change fluid and filter.

My questions are:
1. Are there computer codes stored from the transmission to narrow down the diagnosis?

2. What could be disentegrating in the transmission that involves 1st to 2nd shift?

3. If identifiable, can this be serviced without removing the transmission?

4. Worse case scenario probabilities if this steel part breaks-free and endangers the planetary system?