Major 348 spider transmission problem

My transmission problems appear to be progressively deteriorating.
Planned to change gear oil to see if my transmissions occasional reluctance to go into 1st would decrease.
Removed the transmission drain plug and found it covered with metallic debris.
Cleaned the plug and debris and found my gearbox ate a roller bearing.
Discovered 7 cylinders 0.157” diameter x 0.291” long. The only section of the cage I could find intact enough to estimate diameter is small. Estimate cage to be approximately 1.25”~1.5”diameter, estimate suspect at best.
Reviewing the parts manual, the only Roller Cage bearings I could find that appear to be this small are the Reverse Idler Gear Roller Cage #104734 (2 required) and the 4 Rocker Arm Fork Roller Cage #131895 (1 per Fork/ 4 Forks). The remaining Roller Cage Bearings are related to the various transmission idler gears and appear too large.
Welcome opinions as to which roller bearing failed. The transmission shifts fine, other than the occasional reluctance to go into 1st, makes no unusual noise, grinding, etc. Drove the car prior to the transmission change to warm the fluid. Transmission performed flawlessly.
I suspect the Reverse idle gear roller cage because there are 2 bearings. If the roller cage for the Rocker Arm Fork failed, I suspect I would not be able to shift the gears controlled by that arm.
Can I access the suspect bearings with the transmission in the car?
Opinions welcome. Thank you.

 

Turbo 348, advice well taken. Upon discovery of the bearing failure, I filled the transaxle with fresh fluid and backed the Ferrari into the garage.
My comment was intended to ask what bearing could fail yet not adversely affect transmission perfromance?
Thanks and I will let you know how things develop.

 

Rexrcr, thank you. My computer skills are quite poor. How do I access the old site? I will check the archives. A detailed transmission rebuild report would be incredibly helpful. John.

 

Found the "old" list archives, thank you. My mother always told me "Look with your eyes, not with your mouth" Sorry for the stupid question. Now the search begins for the 348 transmission rebuild posts. Any idea when the post was made? Tried the "search" feature and repeatedly got a negative reply.

 

Rexrcr, thank you again. Very helpful pictures. Appear some "special" tools will need fabrication. Should be oK, I have access to a lathe and a mill. Have to check on a press.
Interesting post, have a friend I email periodically regarding 348 issues in CA also named Carl. Carl has refurbished several 348 transmissions. Same Carl?