Ohm Walsh 4 conundrum.

I'm new here and the main reason I joined is it appears there's lots of Ohm speaker owners at Audiogon. A little background first.  I've owned my 4's since 1986 they were a store demo that were built in 1984. They were refoamed in 1998 by Ohm.  They're driven by a Nakamichi PA-7A MKII amp and CA-7A preamp, TT is a Heybrook tt2 with Linn LVX arm and AT- OC9 ML cart, CD is a Yamaha CD-C600.  The amp and preamp are currently being checked out by a tech who used to do the warranty work for Nakamichi when they were still alive and well.  I'm almost 72 years old and I've noticed a distinct deterioration in the mid bass of the speakers in the past year or so and in general they just don't sound as good as they used to.  I don't suspect there's much wrong with the NAKs, I do reset the bias and offset on the amp and also do the needed adjustments for the pre every 4-5 years myself; but the tech may replace a few caps as they are 30 years old now. I'm doing the electronics first so that I can evaluate any sonic difference after the tech part is done. To upgrade the 4's to Walsh 3000 with shipping (to Canada) is $2100 US which equals $2700 Canadian.  That's a lot of money.  If I refoam them it will cost me $400 Canadian including shipping costs.  My question is....... is there sufficient sonic improvement to justify the cost.... and yes, it's a very subjective question.  My ears are not what they used to be, that said my car stereo hasn't degraded in the past few years so I know it's not just my age. All comments are welcome without prejudice.
The OHM Walsh 3000s are 2000 EACH! Ouch. You might want to call OHM and ask about your options and costs. I hear they are straight shooters. 
Big sound difference between your generation 1 model and current gen 4. I had gen 1 and gen 3 at one time and compared. 

The ohm website lists upgrade options for all models. Start there then call with questions. Yes they are straight shooters.
Most cost effective upgrade will be have new drivers sent and install yourself. Trade in is another option but would have to pay shipping at least one way.

Another trick to take advantage of up to 40% discount if approved for refurb is buy a pair of old ohms cheap on ebay and have them shipped directly to Ohm for trade in. I did that and with sale price at time got my Ohm 5 series 3 for over 50% off list price at the time by trading in two old pair of Ohms for refurb (my original Walsh 2s and C2s fresh off eBay). Check with Ohm first. Trade in speakers must have cabs that can be refurbished. Drivers and electronics do not matter.
Mapman:  You said 'big sound difference between gen 1 model and gen 4'.  What sound difference do you recall between the different versions you had.  As I mentioned in my post my total upgrade cost would be $2700 CDN and a refoam $400 CDN.  I've spoken to John and Evan over the years and I really can't zero in on any changes they've made. It's still an inverted cone with a tweeter kicking in at 8K.  I do know that in the 90's or 2000's they went to an aluminium tweeter for a while and then went back to the soft dome like my 4's have.  That's why I'm reluctant to spend the money for the upgrade
Sent my Walsh 2 in several years ago. Cabinets and all. They relocated the speaker wire hookup,new cans,cleaned up the cabinets to the super 2 2000. Everything mapman says is true,amazing difference. Bass,imagining, all better. It has been said in many other posts,John, the owner knows how to voice a speaker 
better than many others.this is so true. I will never part with these speakers. If and when you can swing the upgrade it is worth it.
Mapman is a long standing Ohm man like I once was. I personaly miss the model F. my favorite for years. Wish I had a good pair to hook-up to todays power amps etc.

I did however "try to upgrade" to the 4.3000 series on my stock 4XOs. Ohm offers a generous in home trial, and you may need every bit of it as I felt was happening. Lifeless, dull, dark, were just a few of my thoughts. Not sure what Ohm does at speaker check-out, but surely cannot be considered a burn in! ( John fix this!)

Mine didnt last the 120 day trial as a right tweeter went dead. I had my funds returned and bought elsewhere, but did take Evan up on a re-foaming of my original XOs ..... which are still sounding very nice. 

What I did notice was how light in weight the new 4.3000 drivers were, seemingly half the weight of my original 4XOs ??? Maybe Mapman can fill us in on this. In any event still a nice speaker at a deicient price, just miss the old days of the wonderful model F. 
My favorites were the A's.....don't remember what they sounded like, just that I loved the speaker....needed Boulder Dam to drive them
  but did take Evan up on a re-foaming of my original XOs ..... which are still sounding very nice.

Thanks Musicbox78.  You've brought out some interesting info that I was not aware of i.e. the weight of the new drivers, that said, lighter weight equals quicker response.  $2000 to trade up sounds like a great deal when new ones cost $4000 a pair but keep in mind 3/4 of the cost of most speakers is the cabinet, labor and overhead.  In my estimation $1500 would be a good deal and $1250 a great deal.  Don't forget shipping is extra and the labor is ours.