I've got a '96 850glt with about 170,000 on it and I am the original owner and main mechanic. Two years ago I had the pnp fail and put in a new dealer bought switch. No further problems for very little work and money. Now, 30k later it rears its ugly head again with the flashing arrow, third gear only routine. Cleared up the flashing arrow with the "ratchet routine" on the shifter. Last time that bought me about a year of peace and quiet. I expect another year this time.
Is this a regular two year item after the original lasted for so long or am I just having a bit of bad luck with this particular one? No leaks under the hoods to contaminate the switch and I don't pressure wash anything or get in any water other than normal rain. I know it is the grease that gums up the switch but is there any preventative to that problem?
A little labor and about $130 will fix it again with total failure, and it is a good investment in a good car, but can I prolong its life with anything other than the shifter ballet?
Anybody got any ideas or experience in multiple failures of this puppy?

Thanks