I have a problem with reverse in my A518, under normal driving it works fine, but under load(like hit gas hard in reverse) it will pop in and out. That is not the worst though yesterday I was in some mud with a load of dirt in the back and in 4low I put it in reverse and all it did was slip and not even spin the tires, had to winch out. I put it in 2wheel and it would spin the rear tire less load, so under full load would not work. Also forward gears all work great and under load no slip. can some one please help what it wrong with reverse

 

Now this is what I did over the weekend, changed filter, adj bands, line pressure all to the sticky, so now it shifts even a little better going forward but still slips in reverse and only when I give it a little gas, or pushing a hold. Everthing forward shots fine.
Can someone please help me and tell me what I should look at next.

 

Could be a cracked reverse servo the stock one is plastic. Could be a broke or burnt reverse band. Is there any hesitation or flare to the 2-3 shift? There is a lip seal on the drum that goes bad and can cause no reverse but it usually causes a flare into 3rd.