I'm not a video Toaster expert, but I can give you few pointers:
1. Try to clean the VT board contacts make sure it's clean, also inspect the board around the chips for any corrosion.
2. Try to run it with out the Indivision ECS, or at least run it in 15khz NTSC mode using the 23 pin video connector (I'm not sure how VT reacts with Indivision ECS)
3. Have a camera input on IN #1 for a good sync, not VCR.
4. Get 2MB Chip ram for best results.
