If you are particularly dextrous, you can change the pad by only removing the top plate - you have to put the new one on the end of a needle and feed it through a gap, but that will not allow you to find where the bits of the old one went. I have often found them stuck to the sliding fingers (below the springs you mention).
The front plate is the one on which the lens is mounted - you have to carefully peel back the letherette and remove the Yashica badge, then 4 screws and the front comes off. Nothing should shoot out - if it does you have a much bigger problem
Have a look for Roger Provins website - he should still have the official Yashica service manual for download. If not let me know and I'll make it available somehow.
BTW - where are you located? If in the US, Greyhoundman might do it for you for a modest sum. If in the UK, I could do it.
Taking the front off is a much better job, and not that difficult if you are careful and record all the things you do, so that you can get it all back together again (the shutter cocking rod can be real fun). Don't be put off - if you can take a digithing down to the sensor, the Yashica should be a doddle