Need TT setup Help

I recently purchased a Orbe Platter upgrade for my Michell Gyrodec Mk1. Prior to the upgrade the rig was set up perfectly. Ive noticed after the platter change something just isnt right. Ive noticed that the Orbe platter is 1/4in taller than the original platter. Could that be the problem here?

the Gyros have a fixed arm height based upon a dedicated armboard
Your explanation about the one fourth inch taller platter is almost certainly the problem. Many cartridges change tonal balance and tracking ability in as little as 5 thousands of an inch. There must be a way to bring this back to the original VTA (height).
You didn't mention what tonearm you are using with your table but FYI,Michell sells a VTA adjusting collar mechanism for the Rega arms that allows raising of the arm.OL,Basis and Express Machining also have similar devices.I have no idea which is the best unit to choose from,tho nor if models exist that fit other tonearms.
I am using a Linn Basic + arm, and last night I reset the stylus pressure weight. I havent had time to see what effect that has. In terms of raising the arm, I am looking at the table now and the clearance between the arms counterweight and the top of the table cover is less than 1/4 inch so I cant see how I would be able to raise the arm of any significance.

any other thoughts would be apprciated.
Hmmm, that's curious -- are you sure the platter's correctly installed and seated on the bearing? I think the best advice would be to contact the US distributor, Artech in VT. Maybe they can help. My guess is that thicker spacers and longer screws could be used to raise the armboard the required amount -- then you might be able to put some thick felt pads under the corners of your dust cover to raise it just enough to clear the arm's counterweight.
To obtain the correct VTA. The suggestions by Caterham1700 will get you the same results as Plato and I, and could provide the ability to adjust the VTA in tiny increments. I think this is a REAL advantage! I recently worked on a VPI TNT, and could not raise the tonearm adequately to get the proper adjustment. After speaking to Harry at VPI, I discovered that the height of the platter could be raised and lowered, extending the range of adjustment. I have no experience with your TT, but as suggested, a call to the distributor would be in order. As far as the dust cover, ask if a taller version is available. If not, a custom cover could be crafted. Look in the Yellow Pages under Plastics and find a dealer with a shop that will build to order. Plexiglas is an ideal material, and available in clear, and several smoked and solid colors. Having control over the proper adjustment of your arm and cartridge would be worth the effort.