Diesel Transmission

Hi All,
I've posted questions in the diesel forum about this, but I figured I would try the tech forum before I spend money on an un-needed tranny.
I have an 82'300d.
First, I had the tranny serviced, and a new modulator put in.
(I remember the tech saying how clean the fluid was)
About 1k later I was taking a trip from philly to baltimore, car ran great all the way, when I got to the first stop light after getting off the hiway- tranny slipped in first gear, but shifted fine thru all other gears, and has been doing that ever since. But only on hard acceleration, if I take it easy, no slip.
Is it possible for vacuum problems to cause this?(noticing problems with the locks)
B2-piston?
Bands?
I would hate to replace a trans that just needed adjustments.
Thanks for any help.
Ed.

[mbdoc]

The most common problems would be with excessive band clearance & the teflon seal for the band piston leaking fluid.

MB DOC
Thanks for the reply.
As a "non mechanic"
Could you give me just a tad more info?
Where should I go from here?

[mbdoc]

The piston for that band can be removed with the trans in the car.
Replacement of the seal is simple & the band can be adjusted at the same time by measuring the clearance & replacing the "adjustment pin" with the corrected size.

Parts would be less than $20. Would take 2-3 hrs at knowledgable shop.