I have just got some new window seals and need to know how to remove the old ones. There appear to be some screws but the heads have rusted and have no slot. Any suggestions?

scream alot..... i had this problem.

i think i drilled a small hole & screwed a small into it & undone it.

it kinda worked i got them all out

Originally there were 3 small Phillips headed countersunk screws holding the lower glass channel. Often you can find these screws and fit a PH screwdriver, give them a tap or 2 with a hammer and most often you can get them out. Recently I found some that I just couldn't budge so I pulled the old channel,out and ground off the heads of the screws with a fine (1mm) cut off blade. Be careful if you do this as the sparks can easily damage the glass surface (cover them up as much as possible).
Once the screws are removed then lower chrome locking strip and glass will come out.