Wow that's interesting! I just shopped my newly acquired BTTF a couple of weeks ago. I noticed that my rubber kit from Marco Specialties came with 3 red flipper rubbers. I had no idea where that third flipper rubber was supposed to go so I figured it was just an "extra". I didn't check the manual, but now that you mentioned it here, I just went to check it out. Sure enough the red flipper rubber does fit around those three metal posts behind the drops along with a regular 1 1/2 inch rubber. Below is a pic on how I installed it as it seems that would be the only way.

flipper rubber on posts.jpg

It seems that the left metal post really takes a beating from the ball as that post screw was broken when I got the pin and I had to replace it with a new post screw and t-nut. Also just now that left post screw was a bit loose and I've only played maybe 30-40 games since I finished shopping it a few weeks ago. The brand new regular 1 1/2 inch rubber had also got a bit of an abrasion from the ball at that left post position. It would make sense to have the extra rubber protection in that area due to the abuse it gets from the ball.

If anyone else has a pic to share of that area it would be appreciated as I'm not really sure if that is the correct installation but it seems like it is correct. Thanks for the heads up as I would have never known!

Here is the Marco part:

http://www.marcospecialties.com/pinball-parts/530-5012-02

You may also need a new t-nut but you can get those at a hardware store:

http://www.marcospecialties.com/pinball-parts/4406-01118-00

You could probably take a regular 2 inch long 6/32 machine screw and screw it up from under the playfield. Slip on the metal post and then just put a regular 6/32 nut on top. I would also put a lock washer under the nut. It should leave enough thread exposed to slip on the metal plate and plastic and still have thread for the plastic acorn nut.

I sort of remember pulling out a totally wasted red flipper rubber from that area when I first opened it up after I got it. I guess I forgot about it a few weeks later when all the parts came in and I started replacing the rubbers. It does make sense to have that extra rubber there as it sure takes a beating.

Another interesting thing is that last night after I made the post here I went looking at Google images to see if I could find a pic of that area. Every pic I found does not show a flipper rubber installed there just the single regular 1 1/2 inch rubber. But of course when you look at the diagram in the manual it does show the flipper rubber being there. Plus it must be so otherwise the 3rd flipper rubber wouldn't be included in the rubber kit.

I'm going to leave that flipper rubber there as I think it will be beneficial. I've played a few games and it seems a lot more solid being there and it doesn't seem to change the game play. Hopefully some other BTTF owners will chime in so that we can get a more definitive answer.

Thanks again for starting this thread!

I knew you were going to ask about were to get the post screws and I had a feeling you were going to ask about the metal plate. Must be reading your mind!!

Yes there is a thin metal plate that is shaped almost the same as the plastic piece and it sits under that plastic. Again I think it's a design feature to strengthen that area and probably helps the plastic piece from absorbing the impact shock and possibly cracking. I'll try to take a pic the next time I take the glass off.

Just checked the manual and I don't see that part listed anywhere.

When I got this pin about a month ago it looked like it still had all the original rubbers and the original balls. The rubbers were all shot and the balls were all rusty. It looks like it may have never been opened once it was on route and then was probably sold that way when taken out of service. The guy I got it from didn't even know how to remove the glass! The MPU was totally battery damaged and it looked like it still had the original batteries from the factory. Didn't even try to repair that board as it was far better to just replace it with a new one. The displays were cracked and dead also so again just got a new one. One of the speakers was dead and one of the drop targets was cracked along with that broken post screw.

So now I have $500 in new boards, $100 in new parts, and almost $200 in new LEDs replacing ALL the bulbs. $800 plus about 10-15 hours work and I almost have a good as new pin! Still need to repaint the side rails, lockdown bar, coin door, and legs and the cabinet artwork on the right side is badly sun faded down to bare wood in some spots. But that's all cosmetic and I'll get to that soon enough.

Right now I'm just enjoying playing this great Back to the Future!!