SP101GP100. reassembly problems

I purchased two of the kits, one for my Sp and the other for my relatively new GP100. .44 Sp/5hot/3". I have started with the GP100, After viewing the instructional video a number of times, (as well as reading the Shooting Times article (that led me to the site and ordering the kits) I commenced on the GP. disassembly was pretty straightforward, these are my 5th and 6th Ruger DA revolvers and I’ve worked on all of the.
Deburring and polishing went fine as did the spring changeover. I was able to get the trigger group reassembled without difficulty. Without the hammer installed, working the trigger DA mode rotates and lock up the cylinder properly and solidly, I can see that the transfer bar is functioning properly.
However I am having problems when reinstalling the hammer------and having it function. I can get it in and pull the trigger, and have the cylinder rotate and lock in place. But I can’t get it to move back the last 1/4 inch or so to either drop the hammer in DA, or have the sear engage for a SA release.
ny I have taken the hammer back out a number of times, checked to assure it is assembled properly reassembled it and re tried----with the same non-result. whatever I’m doing wrong at least I’m being consistent about
I can t see into the action to see if the Hammer, sear, and the hammer dog are engaging properly, It feels like somehow the hammer, hammer dog, and sear are wedging it solid. I’m completely baffled. Any good advice would be appreciated. I’m not a novice at this, Ive tuned Colt and S&W DA Revolvers, Ruger Security Sixes and my highly customized Ruger Redhawk.