zipo

Starting last week the Reverse on my tranny only works immediately after you start the car or come to a complete stop after driving for a while. Any other time you try to select the Reverse the RPM goes up slightly (50-150rpm) but other than that nothing happens, even if you try to accelerate.

After doing some more testing I found out that when the Reverse stops responding if I go from Reverse to Neutral twice the car sloowly starts moving. Also, if I move the lever into Parking position and wait a couple of minutes the Reverse engages once again. Once the Reverse is engaged and you move the lever into any other spot and back to Reverse the gear once again will not respond.

I presume it might be caused by clogged filter, when I did the flush a year ago i couldn't change it b/c there is one nut that I couldn't remove, or I simply need to rebuild my transmission.

I'm looking at four options right now:

1) try replacing the filter
2) add Tranny-X??? not sure if this is a right name. A friend of mine added it to his transmission when his 3rd gear stopped engaging. Six mnth later he is still driving on the same transmission with out "any" problems.
3) get quotes to see how much I would save by removing the transmission my self and brining it to the shop so they could install the kit
4) obtain instructions on how to install the rebuild kit and do everything my self

Things to consider:
It is a 1999 Maxima SE that has 69K miles, sometimes it hits below -40F in the winter, I only drive at full WOT 10%(if not less) of the time.
I have quite a bit of experience of working on cars but I never installed a transmission rebuild kit.

I would greatly appreciate if some one can point out what's wrong or/and the best option to take. So far the only instructions on rebuilding the tranny that I have found are these:

http://www.motorvate.ca/mvp.php/809

zipo

A quick update:

I flushed the transmission oil from the oil pan and added half a bottle of trans-x. After driving the car for 30 miles the reverse now engages every time but the car barely moves even if you try to accelerate. The good thing about this is that I can back-up all the time even if it is at a snail's pace. Once I got home I added the other half of bottle contenants to the tranny.

Anyone has any ideas of what’s going on? I thought that it's something as simple as sludge on the body valve that’s preventing the reverse from engaging but after today I simply don't know.