replacing tonearm question?


Hey,
I have a VPI HW-19 MK4 which I love dearly. My existing Sumiko FT-3 tonearm is 20 years old and on its last legs and I want to replace it with a Jelco 750 or 850. Both arms are 9". Would I have to have a new armboard made and drill new holes? Or could I use the existing armboard and hole and just drill new screws? I know I'd havr to factor in the tonearm radius and all the millimeter differences.

I've never done this before so please excuse my ignorance on this.
128x128simao
@noromance 

If what you say is true, then the manufacturers could use stone bearing balls carved by Fred Flinstones himself if friction isn't important.
The friction heavily affects the suspension of the head, the cantilever, the tracking, going to compromise several elements.
Every detail of an arm is important, but the bearings and clutches they possess must be taken seriously.
That is not what I said or implied. Some false equivalence in your example. My argument is that at 25mg, the amount of friction ceases to be a primary concern. Stability and control of resonance is also important. It should also be noted that these Jelco arms are relatively inexpensive so the value-performance ratio is high.
Because the cartridge has rather extreme leverage over the bearings it would take a pretty bad bearing to dislocate the cantilever one way or the other but the "noise" from a rough bearing can be transferred down the arm to the cartridge. Tap lightly on your tonearm tube towards the bearing end. If you can hear it you can also hear your bearings if they are not absolutely smooth. 
Another fun experiment to determine how well your turntable is isolated. Keep the turntable off and place the stylus down on a stationary record. Turn the volume up and listen to what you get. It should be dead silent other than the noise from your phono amp. If the cartridge is too stiff for the tonearm it will start feeding back wildly. Too loose and the tonearm will start bouncing. All this just from the energy in the room. 
Okay. Quarantine has given me the time to finally do this -- after taking care of other pressing matters, like rearranging my home office, building the boys a pirate ship, tuning and retuning the drum kit, and other really important stuff. 

I have the Jelco schematic and template and Feickerts protractor and all the necessary tools. 

Is there a helpful, step by step video anyone knows of I can have at my side in lieu of a knowledgeable Audiogon member?