L4200 GST Harsh Shift After Repair

I have a 1995 L4200DTGSTC that I purchased last summer with 1940hrs on it. The tractor had some use, but it started fine ran great did not smoke and pulled great. It had one oil leak at the time (left rear axle) which i pulled it down to the break housing and differential and resealed while replacing the axle seal. Well come winter and the cold and it developed leaks in 5 places.
So two weeks ago I decided to pull the cab and split the little gem, to reseal it. We split it at the bell housing, between the mid case and transmission, transmission and differential. While it was apart I replaced the gasket between the GST Valve Body and outer GST Assembly case and noticed the check valve seats (o-rings) were flattened and getting hard. After we got it all back together it now has a harsh and delayed shift when going into gear (1-8 forward or reverse) before the repair it only had a delayed shift when going between 4th and 5th, but was not harsh.
I do have the workshop manual crazy part is the manual shows the parts but the online parts manual does not show the internal GST valve parts. I am a fairly decent auto/diesel tech just new to Kubota.
I will try and check my pressures tomorrow as per the manual but does anyone know if the parts (Check Valve Seats and the Rotary Valve o-rings) are available?
I'd prefer not to have to replace the GST Valve Assembly @ $1800 if I can just rebuild it.

Wolfman, thanks for the reply, not what I would have liked to hear, but was what I figured. I will pull the valve body back off, disassemble it one more time, make sure nothing came apart and clean everything really well to make sure there is nothing causing any of the valves to stick. If that don't work then I will bite the bullet and order a new valve assembly.

After more searching on the web, Yahoo and Google, my wife (yes I have to give her credit) found the parts breakdown of the GST valve assembly. For some reason Kubota has the GST parts breakdown under the L35 model but not the L4200 on their website, and parts are available online through Kubota Dealers. I will order all the o-rings and seals and attempt to go through the valve body.

After more internet searching I came across a post to a thread about an L2900 GST with a slow engage, and one of the post by a member said to check the banjo bolts that are in the on the hyd. lines at the Hyd. Pump, PTO Actuator and GST Assy. and that the banjo bolt for the PTO Actuator has an orfice built into it. This afternoon I finally got some time to check it out and I found that when I reassembled the the tractor after splitting it, I put the banjo bolt with the orfice at the outlet of the Hyd, pump and not at the inlet of the PTO Actuator. After swapping them around everything is working as it should.
If this had not worked I was going to hook up the gauges and check all my pressures. Since I already ordered new o-rings for the GST I will change them when time allows.

Thanks for the info. and support.