Recently I acquired two Infocus projectors, one being the IN78 and the other In76. Both are approximately 11 years old, so parts are very scarce.
The IN78 had lost its red tones which means the colour wheel has faded and obviously requires replacing.
The IN76 had a big, black dot in the centre of the screen which usually means the DMD chip failed or the light magnifying lens is burnt or the light tunnel has collapsed.
Pulling apart the IN76 I discovered the light tunnel had indeed collapsed so i removed and cleaned the tunnel pieces and glued back together with QuickFix UltraRepair. It's flexible, high-temp glue suitable for glass and quick drying too. Put it in the fridge to give it more working time!
Well I switched it on in a still open state however the black dot remained. Next step, remove all other parts just to get the Optical Engine out. Opening the Optical Engine revealed the culprit - an acrylic internal magnifying light lens which was burnt. I'll provide pictures below. Well, I cannot obtain a new lens anywhere unless I find another In72/74/76/78. So, now I've now come to the conclusion that the IN76 is for parts only now. Hence, the colour wheel will be used in the IN78 which is better due to the DMD DarkChip3 technology. What's more, I've now got spare bulbs and parts! Hopefully this helps anyone else with their fault finding or repair.